Draft 2008 California 303(d)/305(b) Integrated Report

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Mammoth Creek, unamed tributary (confluence is near Old Mammoth Rd)
Water Body ID:	CAR6031005120080630162428
Water Body Type:	River & Stream

DECISION ID	8506
Pollutant:	Aluminum
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable water quality objective and criteria. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the applicable objective and criteria and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8506

LOE ID:	7390
Pollutant:	Aluminum
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total recoverable aluminum in 8 samples ranged from 20 to 152 ug/L. The MCLs were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The California primary MCL for aluminum is 1000 ug/L and the secondary MCL is 200 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station, "Mammoth Creek at Twin Lakes" was sampled.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7389
Pollutant:	Aluminum
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved aluminum in eight quarterly samples ranged from 2 to 37 ug/L. The criteria were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The U.S. Environmental Protection Agency's national water quality criteria for aluminum for the protection of freshwater aquatic life are a 4-day average of 87 ug/L and a 1-hour average of 750 ug/L.
Objective/Criterion Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and the Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8509
Pollutant:	Antimony
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable water quality objective and criteria. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the applicable water quality objective and criteria and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8509

LOE ID:	7297
Pollutant:	Antimony
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total antimony in 7 of 8 quarterly samples were estimated values; the remaining sample was below the detection level. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for antimony is 6 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 200 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7296
Pollutant:	Antimony
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved antimony in 8 quarterly samples were all estimated values. The criteria were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The USEPA Lowest Observed Effect Levels (LOEL) criteria for protection of aquatic life include an acute antimony value of 9000 ug/L, a chronic value of 1600 ug/L and a limit for toxicity to algae of 610 ug/L
Objective/Criterion Reference:	Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and the Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8512
Pollutant:	Arsenic
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the California Toxics Rule standards. Eight of the samples exceed the California Maximum Contaminant Level. However, listing is not recommended because the data are not temporally representative. This water body is located within the Long Valley volcanic caldera, and arsenic in the watershed comes from natural volcanic and geothermal sources. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. Eight of eight samples exceeded the MCL and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because, although one of the applicable water quality standards is being exceeded, the data are not temporally representative.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8512

LOE ID:	7288
Pollutant:	Arsenic
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station approximately quarterly under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved arsenic in 8 quarterly samples ranged from 15 to 24 ug/L. The California Toxics Rule standards were not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule arsenic standards for the protection of freshwater aquatic life are as follows: 4-day average = 150 ug/L 1-hour average = 340 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and the Migration of Aquatic Organisms beneficial uses. Arsenic in this watershed comes from natural volcanic and geothermal sources.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7291
Pollutant:	Arsenic
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	8
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total arsenic in 8 quarterly samples ranged from 21 to 30 ug/L. All samples exceeded the MCL.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for arsenic is 10 ug/L (effective November 28, 2008).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. Arsenic in this watershed comes from natural volcanic and geothermal sources.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8515
Pollutant:	Beryllium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable standards or criteria for dissolved beryllium. None of the samples exceed the water quality objective (California Maximum Contaminant Level) for total beryllium. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8515

LOE ID:	7299
Pollutant:	Beryllium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between October 2003 and July 2005. Concentrations of total beryllium in 8 samples were below the detection level. Per Listing Policy Secton 6.1.5.5 the MCL is presumed to be attained.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The California MCL for beryllium is 4 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7298
Pollutant:	Beryllium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved beryllium in 8 quarterly samples were below the detection level.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for dissolved beryllium for the protection of freshwater aquatic life.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8516
Pollutant:	Boron
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the applicable site-specific objective or criterion. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples or three annual average datapoints exceeded the applicable objective or criterion and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8516

LOE ID:	7391
Pollutant:	Boron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station approximately quarterly under the Region 6 SWAMP program between October 2003 and July 2005. The concentrations of dissolved boron in eight quarterly samples were all below the detection level. The criterion was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California State Notification Level criterion for boron is 1000 ug/L.
Objective/Criterion Reference:	Compilation of Water Quality Goals
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	.The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8524
Pollutant:	Boron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station approximately quarterly under the Region 6 SWAMP program between October 2003 and July 2005. The concentrations of dissolved boron in eight quarterly samples were all below the detection level The objective was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The site- specific objective for the Mammoth Creek at Highway 395 station (Lahontan Basin Plan Table 3-17, Station 6) applies through the Tributary Rule. The objective includes an annual average boron concentration of 0.03 mg/L (30 ug/L) and a 90th percentile value of 0.05 mg/L (50 ug/L).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	.The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8517
Pollutant:	Cadmium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two of evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the applicable standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8517

LOE ID:	7307
Pollutant:	Cadmium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved cadmium in 6 of 8 samples were below the detection level, and the remaining two samples were estimated values. The California Toxics Rule standards were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule standards for protection of freshwater aquatic life are dependent on hardness. At the hardness levels reported for this station, the acute toxicity standard ranges from 1.52 to 2.25 ug/L, and the chronic toxicity standard ranges from 1.09 ug/L to 1.44 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
	2007. SWAMP Data for the Owens Hydrologic Unit
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7308
Pollutant:	Cadmium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total cadmium in 4 of 8 samples were below the detection level. Three samples were estimated values, and the total cadmium concentration in the remaining sample was 0.04 ug/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The California MCL for cadmium is 5 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8519
Pollutant:	Calcium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable state or federal standards or criteria for calcium. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. There are no applicable standards or criteria for use with Table 3.2 of the Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because there are no applicable standards or criteria..
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8519

LOE ID:	7386
Pollutant:	Calcium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program approximately quarterly between 2003 and 2005. Concentrations of total calcium in 8 quarterly samples ranged from 12.5 to 20.2 mg/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal water quality standards or criteria for calcium. It is generally monitored as a component of another water quality parameter such as hardness, Total Dissolved Solids, or Sodium Adsorption Ratio.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7385
Pollutant:	Calcium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program approximately quarterly between 2003 and 2005. Concentrations of dissolved calcium in 8 quarterly samples ranged from 14.3 to 20.2 mg/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal water quality standards or criteria for calcium. It is generally monitored as a component of another water quality parameter such as hardness, Total Dissolved Solids, or Sodium Adsorption Ratio.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8525
Pollutant:	Chloride
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There is insufficient information to assess compliance with the site- specific objective because annual average data are available for only three years, and "averages" were calculated on the basis of only 1 to 4 samples per year. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8525

LOE ID:	7425
Pollutant:	Chloride
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005 (1 to 4 samples per year). One of 8 quarterly chloride samples was below the detection level. The remainder ranged from 0.29 to 0.87 mg/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for chloride is 250 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7294
Pollutant:	Chloride
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	1
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. One of 8 quarterly chloride samples was below the detection level. The remainder ranged from 0.29 to 0.87 mg/L. The annual average objective was exceeded in one of three years (the year when the "average" was calculated from one sample).
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The site-specific objective from Lahontan Basin Plan Table 3-17 includes an annual average chloride concentration of 0.8 mg/L and a 90th percentile value of 1.4 mg/L. (The objectives for Station 5, Mammoth Creek at Old Mammoth Road apply under the Tributary Rule).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8528
Pollutant:	Chromium (total)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the applicable water quality objective or California Toxics Rule standards. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the applicable objective and California Toxics Rule standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8528

LOE ID:	7300
Pollutant:	Chromium (total)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved chromium in 8 samples were all below the detection level. Per listing policy Section 6.1.5.5 the California Toxics Rule standards are assumed to be attained.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule (CTR) standards for dissolved Cr VI for protection freshwater aquatic life include a 4-day average of 11 ug/L and a 1-hour average of 16 ug/L. For Cr III, the CTR standards are dependent on hardness. At the hardness levels reported for this station, the acute toxicity standard ranges from 259.67 to 345.23 ug/L, and the chronic toxicity standard ranges from 8424 to 111.99 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7392
Pollutant:	Chromium (total)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total chromium in 7 of 8 quarterly samples were below the detection level. The remaining sample was an estimated value. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for chromium is 50 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005..
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8529
Pollutant:	Cobalt
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable state or federal standards or criteria for cobalt. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. There are no applicable standards or criteria for use with Table 3.1 of the Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because there are no applicable standards or criteria.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8529

LOE ID:	7394
Pollutant:	Cobalt
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total cobalt in 8 quarterly samples ranged from 0.07 to 0.165 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal water quality standards or criteria for cobalt for the protection of human health.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7393
Pollutant:	Cobalt
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved cobalt in 8 quarterly samples ranged from 0.038 to 0.058 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal water quality standards or criteria for cobalt for the protection of aquatic life.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8530
Pollutant:	Copper
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the applicable water quality objective or the California Toxics Rule standards. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of eight samples exceeded the applicable objective and standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8530

LOE ID:	7396
Pollutant:	Copper
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total recoverable copper in 2 of 8 were estimated values. Concentrations in the remaining samples ranged from 0.6 to 1.4 ug/L. The MCLs were not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The primary MCL for copper is 1300 ug/L and the secondary MCL is 1000 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7395
Pollutant:	Copper
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Of 8 quarterly samples, two had dissolved copper concentrations below the detection level, one was an estimated value, and concentrations in the remaining samples were 0.4 and0.7 ug/L The CTR standards were not violated
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule (CTR) freshwater aquatic life standards for copper are dependent on hardness. At the hardness levels reported for this station, the acute toxicity standard ranges from 5.68 to 7.89 ug/L, and the chronic toxicity standard ranges from 4.10 to 5.52 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8532
Pollutant:	Dissolved oxygen saturation
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8532

LOE ID:	7284
Pollutant:	Dissolved oxygen saturation
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Percent saturation of dissolved oxygen in eight quarterly samples ranged from 99 to 107 percent. The objective was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The Lahontan Basin Plan's narrative objective states that percent saturation shall not be depressed by more than 10 percent and minimum dissolved oxygen concentration shall not be less than 80 percent saturation.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station, near the confluence of the tributary with Mammoth Creek, was sampled..
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	Data were collected for an unnamed tributary entering Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. (The lower reach of Mammoth Creek is called Hot Creek.) In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek and its tributaries are designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8534
Pollutant:	Fecal Coliform
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.3 of the Listing Policy. Under section 3.3 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the diel, seasonal and annual variability expected in streamflows and fecal coliform counts in streams of the Lahontan Region. 3. Two of five samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8534

LOE ID:	7423
Pollutant:	Fecal Coliform
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Water Contact Recreation
Number of Samples:	5
Number of Exceedances:	2
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2004 and 2005. Three of five quarterly samples were below the detection level. Fecal coliform bacteria counts in the remaining two samples were 53 and 56 colonies per 100 mL, in violation of the objective.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Five quarterly samples were collected between July 2004 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7421
Pollutant:	Fecal Coliform
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	5
Number of Exceedances:	2
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2004 and 2005. Three of five quarterly samples were below the detection level. Fecal coliform bacteria counts in the remaining two samples were 53 and 56 colonies per 100 mL, in violation of the objective.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Five quarterly samples were collected between July 2004 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9263
Pollutant:	Hardness
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable state or federal standards or criteria for hardness. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. There are no applicable water quality standards or criteria. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because there are no applicable water quality standards or criteria.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9263

LOE ID:	8548
Pollutant:	Hardness
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled the Mammoth Creek tributary for hardness between 2003 and 2005 under the Region 6 SWAMP program. Calculated hardness in 8 quarterly samples ranged from 40.11 to 56.20 mg/L CaCO3.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for hardness. Hardness is monitored for purposes such as determination of the applicable criteria and standards for metals whose toxicity is hardness-dependent. The U.S. Environmental Protection Agency's 1986 "Gold Book" includes generally accepted categories of hardness. Calcium and magnesium are the major ions contributing to hardness, and hardness is generally expressed as calcium carbonate. Water with a hardness of 0 to 75 mg equivalent CaC03/L is considered "soft."
Objective/Criterion Reference:	Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8549
Pollutant:	Hardness
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled the Mammoth Creek tributary for hardness between 2003 and 2005 under the Region 6 SWAMP program. Calculated hardness in 8 quarterly samples ranged from 40.11 to 56.20 mg/L CaCO3.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for hardness. Hardness is monitored for purposes such as determination of the applicable criteria and standards for metals whose toxicity is hardness-dependent. The U.S. Environmental Protection Agency's 1986 "Gold Book" includes generally accepted categories of hardness. Calcium and magnesium are the major ions contributing to hardness, and hardness is generally expressed as calcium carbonate. Water with a hardness of 0 to 75 mg equivalent CaC03/L is considered "soft."
Objective/Criterion Reference:	Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8537
Pollutant:	Iron
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the applicable water quality objective or aquatic life criterion. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the applicable objective and criterion and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8537

LOE ID:	7397
Pollutant:	Iron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Dissolved iron concentrations in 7 of 8 quarterly samples were below the detection level, and the remaining sample was an estimated value. The criterion was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The U.S. Environmental Protection Agency's national freshwater aquatic life criterion for iron is a 4-day average of 1000 ug/L.
Objective/Criterion Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7400
Pollutant:	Iron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Total recoverable iron concentrations in 8 quarterly samples ranged from 20 to 160 ug/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for iron is 300 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8540
Pollutant:	Lead
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the applicable water quality objective (California Maximum Contaminant Level) or California Toxics Rule standards. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the applicable standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8540

LOE ID:	7406
Pollutant:	Lead
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between 2003 and 2005. The total lead concentration in one of eight samples was an estimated value. The remaining concentrations ranged from 0.07 to 0.42 ug/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for lead is 15 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7405
Pollutant:	Lead
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Dissolved lead concentrations in 7 of 8 quarterly samples were below the detection level. The remaining sample was an estimated value. The CTR standards were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule’s freshwater aquatic life standards for lead are dependent on hardness. At the hardness levels reported for this station, the acute toxicity standard ranges from 20.19 to 31.43 ug/L. The chronic toxicity standard ranges from 0.79 to 1.22 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses. Arsenic in this watershed comes from natural volcanic and geothermal sources.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9266
Pollutant:	Magnesium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable water quality standards or criteria for total magnesium or dissolved magnesium. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. There are no applicable water quality standards or criteria. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because there are no applicable water quality standards or criteria.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9266

LOE ID:	7388
Pollutant:	Magnesium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total magnesium in 8 quarterly samples ranged from 1 to 1.44 mg/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal water quality standards or criteria for magnesium. It is generally monitored as a component of another water quality parameter such as hardness, Total Dissolved Solids, or Sodium Adsorption Ratio.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7387
Pollutant:	Magnesium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program quarterly between 2003 and 2005. Concentrations of dissolved magnesium in 8 samples ranged from 1.07 to 1.42 mg/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal water quality standards or criteria for magnesium. It is generally monitored as a component of another water quality parameter such as hardness, Total Dissolved Solids, or Sodium Adsorption Ratio.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8544
Pollutant:	Manganese
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable standards or criteria for manganese for the protection of aquatic life. None of the samples exceeds the applicable water quality objective (California Maximum Contaminant Level). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. There are no applicable aquatic life standards or criteria. None of 8 samples exceeded the California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8544

LOE ID:	7409
Pollutant:	Manganese
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved manganese in 4 of 8 smaples were estimated values; the remainder ranged from 0.3 to 0.5 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for manganese for the protection of freshwater aquatic life.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7410
Pollutant:	Manganese
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total manganese in 8 quarterly samples ranged from 1 to 7 ug/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for manganese is 50 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9277
Pollutant:	Mercury
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. Six of the samples exceed the California Toxics Rule (CTR) human health standard. However, listing is not recommended because the data are not temporally representative. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy in that quarterly samples do not reflect the expected seasonal and annual variation in streamflows and constituent concentrations in the Lahontan Region. 3. Six of 8 samples exceed the CTR standard and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because, although one of the applicable water quality standards is being exceeded, the data are not temporally representative.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9277

LOE ID:	8598
Pollutant:	Mercury
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	6
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total mercury in eight quarterly samples ranged from 0.04 to 0.30 ug/L. Six of eight samples exceeded the CTR standard.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule (CTR) human health standard for consumption of water and organisms is 0.05 ug/L as a 30 day average.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and the Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8553
Pollutant:	Mercury
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Five of 8 samples for dissolved mercury were below the detection level, two were estimated values, and the concentration in the remaining sample was 0.01 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no state or federal criteria for dissolved mercury for the protection of human health.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8604
Pollutant:	Mercury
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Five of 8 samples for dissolved mercury were below the detection level, two were estimated values, and the concentration in the remaining sample was 0.01 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no applicable California or federal aquatic life criteria for dissolved mercury. The U.S. Environmental Protection Agency's national freshwater aquatic life criteria are expressed as total mercury (including inorganic and organic mercury). Total mercury data for this station are assessed in separate Lines of Evidence.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and the Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8594
Pollutant:	Mercury
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total mercury in eight quarterly samples ranged from 0.04 to 0.30 ug/L. The criteria were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The U.S. Environmental Protection Agency's national freshwater aquatic life criteria (for total mercury) include a 4-day average of 0.77 ug/L and a 1-hour average of 1.4 ug/L.
Objective/Criterion Reference:	National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and the Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8550
Pollutant:	Molybdenum
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable standards or criteria for molybdenum. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not sQuarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region.atisfy the data quantity requirements of section 6.1.5 of the Policy. 3. There are no applicable aquatic life standards or criteria and the data cannot be assessed using Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because there are no applicable water quality standards or criteria.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8550

LOE ID:	7412
Pollutant:	Molybdenum
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program quarterly between 2003 and 2005. Concentrations of total molybdenum in 8 samples ranged from 0.8 to 1.3 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no applicable water quality standards or criteria for molybdenum for protection of the Municipal and Domestic Supply use..
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7411
Pollutant:	Molybdenum
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved molybdenum in 8 quarterly samples ranged from 0.8 to 1.3 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal water quality standards or criteria for molybdenum for the protection of aquatic life.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9267
Pollutant:	Nickel
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of seven dissolved nickel samples or 8 total nickel samples samples exceeded the California Toxics Rule standards or the California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9267

LOE ID:	7414
Pollutant:	Nickel
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total nickel in eight quarterly samples rangedfrom 0.32 to 0.74 ug/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nickel is 100 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7413
Pollutant:	Nickel
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	7
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program quarterly between 2003 and 2005. Concentrations of dissolved nickel in 7 samples ranged from 0.2 to 0.88 ug/L. The CTR standards were not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule (CTR) freshwater aquatic life standards for nickel are dependent on hardness. At the hardness levels reported for this station, the acute toxicity standard ranges from 216.18 to 290.12 ug/L, and the chronic toxicity standard ranges from 24.04 to 32.26 ug/L
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Seven quarterly samples were collected between 2001 and 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses. Arsenic in this watershed comes from natural volcanic and geothermal sources.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9268
Pollutant:	Nitrate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two of evidence are available in the administrative record to assess this pollutant. None of the annual average datapoints exceed the site-specific water quality objective. None of the samples exceed the California Maximum Contaminant Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None 8 samples exceeded the California Maximum Contaminant Level. None of 3 annual average datapoints exceed the site-specific objective. This does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9268

LOE ID:	8590
Pollutant:	Nitrate
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Eight quarterly samples each were analyzed for nitrite and nitrite plus nitrate. Nitrate was calculated by subtraction. Nitrate concentrations ranged from 0.010 mg/L to 0.121 mg/L, expressed "as N". The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrate is 45 mg/L expressed "as nitrate." This is equivalent to 10 mg/L expressed "as N."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples each for nitrite and nitrite plus nitrate were collected quarterly (1 to 4 samples per constituent per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8575
Pollutant:	Nitrate
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Eight quarterly samples each were analyzed for nitrite and nitrite plus nitrate. Nitrate was calculated by subtraction. Nitrate concentrations ranged from 0.010 mg/L to 0.121 mg/L, expressed "as N". Annual average concentrations, expresed "as nitrate" ranged from 0.081 to 0.329 mg/L. The annual average objective was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The site-specific objective for nitrate (expressed "as nitrate") from Lahontan Basin Plan Table 3-17 includes an annual average concentration of 0.4 mg/L and a 90th percentile value of 0.8 mg/L. (The objectives for Station 5, Mammoth Creek at Old Mammoth Road apply under the Tributary Rule).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples each for nitrite and nitrite plus nitrate were collected quarterly (1 to 4 samples per constituent per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9269
Pollutant:	Nitrate/Nitrite (Nitrite + Nitrate as N)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9269

LOE ID:	8552
Pollutant:	Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of nitrite plus nitrate in 8 quarterly samples ranged from 0.011 to 0.122 mg/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrite plus nitrate (expressed "as N") is 10 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	15569
Pollutant:	Nitrite
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of 8 samples exceeded the California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 15569

LOE ID:	26262
Pollutant:	Nitrite
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Eight quarterly samples all had nitrite concentrations of 0.001 mg/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrite is 1 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8553
Pollutant:	Oxygen, Dissolved
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the water qualitiy objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8553

LOE ID:	7282
Pollutant:	Oxygen, Dissolved
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. The dissolved oxygen concentrations in 8 quarterly samples ranged from 9 to 10.7 mg/L. The objective was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The objective, from Lahontan Basin Plan Table 3-6, is a one- day minimum dissolved oxygen concentration of 8 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station, near the confluence of the tributary with Mammoth Creek, was sampled..
Temporal Representation:	Eight samples were collected quarterly between October 2003 and July 2005.
Environmental Conditions:	Data were collected for an unnamed tributary entering Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. (The lower reach of Mammoth Creek is called Hot Creek.) In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek and its tributaries are designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9271
Pollutant:	Phosphate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the annual average datapoints exceeds the site-specific water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of three annual average datapoints exceeded the site-specific objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9271

LOE ID:	8578
Pollutant:	Phosphate
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of phosphate "as P" in 8 samples ranged from 0.013 to 0.029 mg/L. Calculated concentrations of phosphate "as phosphate" in 8 samples ranged from 0.040 to 0.089. Annual averages for three years ranged from 0.061 to 0.077 mg/L. The annual average objective was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The site-specific objective for dissolved orthophosphate from Lahontan Basin Plan Table 3-17 includes an annual average concentration of 0.27 mg/L and a 90th percentile value of 0.50 mg/L. (The objectives for Station 5, Mammoth Creek at Old Mammoth Road apply under the Tributary Rule).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples for phosphate "as P" were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9272
Pollutant:	Phosphorus
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. No biological data are available for assessment whether the chemical samples comply with the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. No biological data were available for assessment of compliance with the objective for biostimulatory substances. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because no biological data are available for assessment whether the chemical data comply with the water quality objective.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9272

LOE ID:	8591
Pollutant:	Phosphorus
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Reported concentrations of total phosphorus in 8 quarterly samples ranged from 0.024 to 0.042 mg/L. No biological data are available for use in assessing compliance with the objective for biostimulatory substances.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There is no applicable site-specific objective (SSO)for Total Phosphorus for this creek. (Lahontan Basin Plan Table 3-17 includes an SSO for dissolved orthophosphate.) The regionwide narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples for total phosphorus were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9276
Pollutant:	Sediment
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	The Lahontan Basin Plan's narrative water quality objective is an antidegradation based objective that provides that there shall be no increases in suspended sediment concentrations or loads. This pollutant is being considered for placement on the section 303(d) list under section 3.10 of the Listing Policy, which deals with trends in water quality. One line of evidence, based on quarterly sampling, is available in the administrative record to assess this pollutant. It includes 8 suspended sediment concentration values and 8 suspended sediment load values calculated from instantaneous discharge measurements. Suspended sediment concentrations and loads are dependent on flows and can change rapidly over a short time during storm or snowmelt runoff events. Quarterly samples are insufficient to capture these short term events and therefore are insufficient to define natural background suspended sediment concentrations and loads, or to detect trends. Listing Policy Section 3.10 requires that natural background conditions be established. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. Sampling frequency was insufficient to establish natural background conditions and therefore does not meet the requirements of Listing Policy Section 3.10. 3. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because the available data are insufficient to meet the requirements of Listing Policy Section 3.10.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9276

LOE ID:	7422
Pollutant:	Sediment
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of suspended sediment in 8 quarterly samples ranged from 2 to 19 mg/L. The USGS did 8 sediment discharge (load) calculations using quarterly flow (discharge) measurements taken concurrently with the sediment samples. Five of the eight flow measurements were estimates. The remaining instantaneous discharge flows ranged from 0.32 to 0.8 cubic feet per second. Six of the calculated sediment loads were below detection level. The remaining two samples had sediment loads of 0.02 and 0.04 tons per day.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The Lahontan Basin Plan's objective states: "The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight suspended samples were collected quarterly between October 2003 and July 2005. Eight sediment load calculations were done.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8554
Pollutant:	Selenium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable California Toxics Rule and Maximum Contaminant Level standards. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the California Toxics Rule or Maximum Contaminant Level standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8554

LOE ID:	7415
Pollutant:	Selenium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved selenium in 2 of 8 quarterly samples were below the detection level. The remaining samples were estimated values. The California Toxics Rule standards were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule (CTR) selenium standards for the protection of freshwater aquatic life are as follows: 4-day average = 5.0 ug/L; 1-hour average = 20 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south.. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses. Arsenic in this watershed comes from natural volcanic and geothermal sources.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7416
Pollutant:	Selenium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station quarterly under the Region 6 SWAMP program between 2003 and 2005. One of 8 samples for total selenium was below the detection level, 3 samples were estimated values, and total selenium concentrations in the remaining samples ranged from 0.5 to 0.7 ug/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for selenium is 50 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8556
Pollutant:	Silver
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable California Toxics Rule or Maximum Contaminant Level standards. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the applicable California Toxics Rule or Maximum Contaminant Level standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8556

LOE ID:	7301
Pollutant:	Silver
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program quarterly between 2003 and 2005. Concentrations of dissolved silver in 8 samples were below the detection level. Per Listing Policy Section 6.1.5.5, the CTR standards were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule (CTR) freshwater aquatic life standard for silver is dependent on hardness. .At the hardness levels reported for this station, the instantaneous maximum standard ranges from 0.72 to 1.30 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses. Arsenic in this watershed comes from natural volcanic and geothermal sources.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7302
Pollutant:	Silver
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total silver in 8 samples were below the detection level. Per Listing Policy section 6.1.5.5, the MCL was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for silver is 100 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between 2001 and 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8559
Pollutant:	Specific Conductance
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective (California Maximum Contaminant Level). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data do not used satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8559

LOE ID:	7295
Pollutant:	Specific Conductance
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Specific conductance in 8 quarterly field measurements ranged from 72 to 124 uS/cm. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for specific conductance is 900 microsiemens per centimeter (uS/cm).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight field measurements of specific conductance were taken quarterly between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9275
Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	The Lahontan Basin Plan's narrative temperature objective is an antidegradation-based objective that requires that there be no change in temperature in waters designated for the Cold Freshwater Habitat (COLD) beneficial use. The objective does not include specific numerical limits for protection of the COLD use. Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects. One line of evidence is available to support this decision. There are not enough temperature samples to establish baseline conditions (including diel, seasonal, annual and interannual variations in temperature) or to detect declining trends in the temperature regime if such trends exist. Because temperature samples were collected only quarterly, weekly and monthly average data are not available for comparison with guidelines in the scientific literature for the temperature requirements of sensitive aquatic species such as salmonids, as directed in Listing Policy Section 6.1.5.9.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because the available data are not sufficient to meet the requirements of Listing Policy sections 3.10 and 6.1.5.9.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9275

LOE ID:	7286
Pollutant:	Temperature, water
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Water temperatures in 8 quarterly measurements ranged from 0 to 9.5 degrees Celsius.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The applicable language from the Lahontan Basin Plan's temperature objective states: "The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses. For waters designated WARM, water temperature shall not be altered by more than five degrees Fahrenheit ... above or below the natural temperature. For waters designated COLD, the temperature shall not be altered."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station, near the confluence of the tributary with Mammoth Creek, was sampled.
Temporal Representation:	Eight temperature measurements were taken quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8561
Pollutant:	Thallium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of 8 samples exceeded the applicable aquatic life criteria or California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards and criteria are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8561

LOE ID:	7304
Pollutant:	Thallium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved thallium in 8 quarterly samples were below the detection level. Per Listing Policy section 6.1.5.5, the MCL was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The U.S. Environmental Protection Agency's Lowest Observed Effect Levels (LOEL) criteria include an acute toxicity value of 1400 ug/L,and a chronic toxicity value of 40 ug/L. The criteria also include an "Other" limit of 20 ug/L based on 2600 hour exposure of one fish species..
Objective/Criterion Reference:	Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7306
Pollutant:	Thallium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of total recoverable thallium in 8 quartely samples were below the detection level. Per Listing Policy section 6.1.5.5, the MCL was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for thallium is 2 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between 2001 and 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9265
Pollutant:	Total Dissolved Solids
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the California Maximum Contaminant Level (MCL). One annual average datapoint exceeds the site-specific objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of 8 samples exceeded the MCL and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. One of three annual average datapoints exceeded the site-specific objective, and the three datapoints do not meet the minimum sample number requirements of Table 3.2. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9265

LOE ID:	8550
Pollutant:	Total Dissolved Solids
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	1
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of TDS in 8 quarterly samples ranged from 78 to 90 mg/L. Annual average concentrations (based on 1 to 4 samples per year) ranged from 82 to 86 mg/L. The annual average objective was exceeded in one of three years.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The site-specific objective from Lahontan Basin Plan Table 3-17 includes an annual average Total Dissolved Solids (TDS) concentration of 85 mg/L and a 90th percentile value of 115 mg/L. (The objectives for Station 5, Mammoth Creek at Old Mammoth Road apply under the Tributary Rule.).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8551
Pollutant:	Total Dissolved Solids
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of TDS in 8 quarterly samples ranged from 78 to 90 mg/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The recommended MCL for Total Dissolved Solids (TDS) is 500 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9273
Pollutant:	Total Kjeldahl Nitrogen (TKN)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. No biological data are available for assessment whether the chemical data comply with the water quality objective for biostimulatory substances. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. No biological data are available for assessment whether the chemical data comply with the objective. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because no biological data are available for assessment of compliance with the objective.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9273

LOE ID:	8589
Pollutant:	Total Kjeldahl Nitrogen (TKN)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Reported concentrations of TKN in 8 quarterly samples ranged from 0.04 to 0.15 mg/L. No biological data are available for use in assessing compliance with the objective for biostimulatory substances.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There is no applicable site-specific objective (SSO)for Total Kjeldahl Nitrogen (TKN) for this creek. (Lahontan Basin Plan Table 3-17 includes SSOs for nitrate and total nitrogen.) The regionwide narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples for TKN were collected quarterly (1 to 4 samples per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9270
Pollutant:	Total Nitrogen as N
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the annual average datapoints exceed the site-specific water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of three annual average datapoints exceeded the site-specific objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9270

LOE ID:	8554
Pollutant:	Total Nitrogen as N
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Total N was calculated from total Kjeldahl nitrogen (TKN) and nitrite plus nitrate (from 8 quarterly samples of each). Concentrations of total nitrogen ranged from 0.081 to 0.322 mg/L. Annual average values ranged from 0.089 to 0.188. The annual average objective was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The site-specific objective for total nitrogen from Lahontan Basin Plan Table 3-17 includes an annual average concentration of 0.6 mg/L and a 90th percentile value of 1.0 mg/L. (The objectives for Station 5, Mammoth Creek at Old Mammoth Road apply under the Tributary Rule).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight samples each for TKN and nitrite plus nitrate were collected quarterly (1 to 4 samples per constituent per year) between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	9274
Pollutant:	Turbidity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. None of the samples measured as NTU exceed the California Maximum Contaminant Level (MCL). Compliance with the MCL cannot be determined for samples measured as NTRU. The Lahontan Basin Plan's narrative turbidity objective is non-degradation based and the turbidity data are insufficient to establish baseline conditions and detect trends as required under Listing Policy section 3.10. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the diel, seasonal and annual variability expected in streamflows and turbidity in streams of the Lahontan Region. 3. None of four samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. (The minimum sample number requirements of Table 3.2 are not met.) The limited data do not meet the requirements of Section 3.10 for assessment of baseline and trend conditions. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because one of the applicable water quality standards is not being exceeded and there is insufficient information to assess compliance with the other standard.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 9274

LOE ID:	8545
Pollutant:	Turbidity
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled the Mammoth Creek tributary in 2004 and 2005 as part of Region 6's SWAMP program. Four turbidity measurements expressed as NTRU included three below the detection level, and one with a turbidity of 2.3 NTRU. Sampling frequency was insufficient to characterize the normal turbidity regime or to allow identification of changes in this regime or effects on beneficial uses.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal standards or criteria for protection of aquatic life that are expressed as NTRU.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Four quarterly turbidity measurements expressed as NTRU were taken between October 2004 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8547
Pollutant:	Turbidity
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled the Mammoth Creek tributary in 2004 and 2005 as part of Region 6's SWAMP program. Four turbidity measurements expressed as NTRU included three below the detection level, and one with a turbidity of 2.3 NTRU.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal standards or criteria for the protection of human health for turbidity expressed as NTRU.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Four quarterly turbidity measurements expressed as NTRU were taken between October 2004 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8544
Pollutant:	Turbidity
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled the Mammoth Creek tributary in 2003 and 2004 as part of Region 6's SWAMP program. Four turbidity measurements expressed as NTU included two below the detection level, and two measurements with turbidities of 3.1 and 3.4 NTU. Sampling frequency was insufficient to characterize the normal turbidity regime or to allow identification of changes in this regime or effects on beneficial uses.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The Lahontan Basin Plan's regionwide water quality objective states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Four quartelry turbidity measurements expressed as NTU were taken between October 2003 and July 2004.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	8546
Pollutant:	Turbidity
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled the Mammoth Creek tributary in 2003 and 2004 as part of Region 6's SWAMP program. Four turbidity measurements expressed as NTU included two below the detection level, and two measurements with turbidities of 3.1 and 3.4 NTU. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Four quartelry turbidity measurements expressed as NTU were taken between October 2003 and July 2004.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use,
QAPP Information:	The data meet quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8564
Pollutant:	Vanadium
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable aquatic life standards or criteria. None of the samples exceed the California Notification Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. There are no applicable standards or criteria for protection of aquatic life. None of 8 samples exceeded the California Notification Level criterion and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8564

LOE ID:	7418
Pollutant:	Vanadium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program quarterly between 2003 and 2005. Concentrations of total vanadium in 5 of 8 samples were below the detection level. The presence of vanadium in the remaining 3 samples was verified but not quantified. The criterion was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Notification Level criterion for vanadium in drinking water is 50 ug/L.
Objective/Criterion Reference:	Drinking Water Notification and Response Levels: An overview
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7417
Pollutant:	Vanadium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved vanadium in 8 quarterly samples ranged from 0.2 to 0.4 ug/L.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	There are no California or federal standards or criteria for dissolved vanadium for the protection of freshwater aquatic life.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	8565
Pollutant:	Zinc
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable California Toxics Rule standards or the California Maximum Contaminant Level objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the applicable California Toxics Rule or Maximum Contaminant Level standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 8565

LOE ID:	7420
Pollutant:	Zinc
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station approximately quarterly under the Region 6 SWAMP program between 2003 and 2005. Of 8 samples for total zinc, three were estimated values. Concentrations of total recoverable zinc in the remaining 5 samples ranged from 2 to 4 ug/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for zinc is 5 mg/L, equivalent to 5000 ug/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek.
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	7419
Pollutant:	Zinc
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of dissolved zinc in 8 quarterly samples ranged from 1 to 3.1 ug/L. The standards were not violated.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The California Toxics Rule freshwater aquatic life standards for zinc are dependent on hardness. At the hardness levels reported for this station, the acute toxicity standard ranges from 54.04 to 71.91 ug/L, and the chronic toxicity standard ranges from 54.48 to 72.50 ug/L.
Objective/Criterion Reference:	Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	The tributary was sampled at one station near its confluence with Mammoth Creek..
Temporal Representation:	Eight quarterly samples were collected between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses. Arsenic in this watershed comes from natural volcanic and geothermal sources.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	15570
Pollutant:	pH
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	New Decision
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant
Weight of Evidence:	The Lahontan Basin Plan's narrative pH objective is an antidegradation-based objective that requires that there be no change greater than 0.5 pH units in waters designated for the Cold Freshwater Habitat (COLD) or Warm Freshwater Habitat beneficial uses. Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects. One line of evidence is available to support this decision. There are not enough pH samples to establish baseline conditions (including diel, seasonal, annual and interannual variations) or to detect changes in the pH regime due to controllable factors, if such trends exist.
RWQCB Board Decision / Staff Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 15570

LOE ID:	26263
Pollutant:	pH
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	8
Number of Exceedances:	0
Data and Information Type:	Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality:	The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2003 and 2005. The pH in 8 quarterly field measurements ranged from 7.2 to 7.8 units.
Data Reference:	2007. SWAMP Data for the Owens Hydrologic Unit
Water Quality Objective/Criterion:	The Lahontan Basin Plan's objective for pH states: "In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station, near the confluence of the tributary with Mammoth Creek, was sampled.
Temporal Representation:	Eight pH measurements were taken quarterly between October 2003 and July 2005.
Environmental Conditions:	The unnamed tributary enters Mammoth Creek from the south. Mammoth Creek is a tributary of the Owens River with headwaters near the Sierra Nevada crest. The lower reach of Mammoth Creek is influenced by geothermal springs and is called Hot Creek. In addition to the Cold Freshwater Habitat beneficial use, Mammoth Creek is designated for the Spawning, Reproduction and Development and Migration of Aquatic Organisms beneficial uses.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):