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

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Littlerock Reservoir
Water Body ID:	CAL6268000020020529143312
Water Body Type:	Lake & Reservoir

DECISION ID	10931
Pollutant:	Alkalinity, Carbonate as CaCO3
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 datapoints exceeds the water quality 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 (from only one or two sampling runs per year) do not satisfy the data quantity requirements of section 6.1.5 of the Policy. The limited sampling frequency was insufficient to document seasonal and annual variation. 3. None of 4 datapoints exceeded the criterion and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. However, the minimum sample number requirements of Table 3.2 are not met. 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 the minimum sample number requirements of the Listing Policy are not met..
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10931

LOE ID:	23518
Pollutant:	Alkalinity, Carbonate as CaCO3
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. Alkalinity was reported for a total of 8 samples (1 to 3 per day). Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Alkalinity values for the four sampling dates were as follows: 340, 280, 220 (estimated) and 78 mg/L CaCO3/L. The criterion was not violated.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The USEPA's national water quality criteria recommend a minimum hardness of 20 mg/L calcium carbonate as a chronic criterion for the protection of aquatic life, unless the natural alkalinity level is lower.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10936
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 California State Notification Level criterion. Three out of three "annual average" datapoints (calculated from only one or two daily average datapoints per year) exceed the water quality objective. Listing is not recommended because the samples are not temporally representative. 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 satisfies 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. Three of three "annual average" datapoints, based on limited sample numbers, exceeded the site specific objective 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:
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10936

LOE ID:	6195
Pollutant:	Boron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	3
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 boron samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average boron concentrations on the four sampling dates were as follows: (10/28/2001) 60 ug/L; (5/7/2002) 79 ug/L; (10/24/2002) 104 ug/L; and (3/20/2003) 33 ug/L. "Annual averages" calculated from one or two datapoints exceeded the objective in three of three years.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The site-specific objective (in Lahontan Basin Plan Table 3-19) includes an annual average of 0.03 mg/L (or 30 ug/L) and a 90th percentile value of 0.05 mg/L (or 50 ug/L).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight boron samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	23511
Pollutant:	Boron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 boron samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average boron concentrations on the four sampling dates were as follows: (10/28/2001) 60 ug/L; (5/7/2002) 79 ug/L; (10/24/2002) 104 ug/L; and (3/20/2003) 33 ug/L. The California State Notification Level was not exceeded.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The California State Notification Level for boron is 1000 ug/L.
Objective/Criterion Reference:	Drinking Water Notification and Response Levels: An overview
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight boron samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10939
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 (from only one or two sampling runs per year) do not satisfy the data quantity requirements of section 6.1.5 of the Policy. The limited sampling frequency was insufficient to document seasonal and annual variation. 3. There are no applicable water quality standards or criteria and the data cannot be assessed using 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 there are no applicable water quality standards or criteria..
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10939

LOE ID:	23513
Pollutant:	Calcium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 samples for dissolved calcium (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Calcium concentrations for the four sampling dates were as follows: 88.9 mg/L, 70.5 mg/L, 35.2 mg/L, and 19.9 mg/L.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for dissolved calcium.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7765
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 3.1 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 datapoints (including transformed data) exceed the applicable water quality objectives. However, the four available datapoints (and three annual average datapoints) do not meet the minimum sample number requirements of Listing Policy Table 3.2. 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 requirement of section 6.1.5 of the Listing Policy..The limited sampling frequency was insufficient to document seasonal and annual variation in constituent concentrations. 3. None of the____ datapoints is in violation of appliable water quality standards and this does not _________ of Table 3.2 of the Policy. The minimum sample number requirements of Table 3.2 were not met 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 the minimum sample number requirements of the Listing Policy were not met.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7765

LOE ID:	6011
Pollutant:	Chloride
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 chloride samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average chloride concentrations on the four sampling dates were as follows: (10/28/2001) 9.71 mg/L; (5/7/2002) 8.45 mg/L; (10/24/2002) 10.6 mg/L; and (3/20/2003) 3.24 mg/L. The annual average objective was not violated.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The site-specific objective (in Lahontan Basin Plan Table 3-19) includes an annual average of 12.5 mg/L and a 90th percentile value of 20.0 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
	2007. SWAMP Data for the Antelope Hydrologic Unit.
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight chloride samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	6012
Pollutant:	Chloride
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 chloride samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average chloride concentrations on the four sampling dates were as follows: (10/28/2001) 9.71 mg/L; (5/7/2002) 8.45 mg/L; (10/24/2002) 10.6 mg/L; and (3/20/2003) 3.24 mg/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Antelope 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:	One station was sampled on each sampling date.
Temporal Representation:	Eight chloride samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7761
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. Two lines of evidence are available in the administrative record to assess this pollutant. However, only four samples were taken and this does not meet the minimum sample number requirement of Listing Policy Table 3.2. 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 requirement of section 6.1.5 of the Policy. The limited sampling frequency (one or two samples per year) was insufficient to document seasonal and annual variation in fecal coliform counts, and the water quality objective calls for collection of five samples in a 30- day period. 3.None of 4 fecal coliform datapoints exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. The minimum sample number requirements of Table 32 are not met.. 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 do not meet the minimum sample numbers required by the Listing Policy.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7761

LOE ID:	5711
Pollutant:	Fecal Coliform
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:	Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality:	The U. S. Geological Survey sampled Lilttlerock Reservoir under the Region 6 SWAMP program on four different dates in 2001, 2002 and 2003. Fecal coliform counts in four samples were all estimated values. The objective was not exceeded.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The Lahontan Basin Plan's regionwide 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).
	2007. SWAMP Data for the Antelope Hydrologic Unit.
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station in Littlerock Reservoir was sampled for fecal coliform bacteria
Temporal Representation:	Four fecal coliform samples were collected between 2001 and 2003.
Environmental Conditions:	Littlerock (sometimes spelled "Little Rock") Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	5712
Pollutant:	Fecal Coliform
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	None
Beneficial Use:	Water Contact Recreation
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality:	The U. S. Geological Survey sampled Lilttlerock Reservoir under the Region 6 SWAMP program on four different dates in 2001, 2002 and 2003. Fecal coliform counts in four samples were all estimated values. The objective was not exceeded.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The Lahontan Basin Plan's regionwide 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:	One station in Littlerock Reservoir was sampled for fecal coliform bacteria.
Temporal Representation:	Four samples were collected between 2001 and 2003.
Environmental Conditions:	Littlerock (sometimes spelled "Little Rock") Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10934
Pollutant:	Fluoride
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 datapoints exceeds the California Maximum Contaminant Level.(MCL). Two of three 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 do not satisfy the data quantity requirements of section 6.1.5 of the Policy. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. None of 4 datapoints exceeded the MCL. Two of three annual average datapoints exceeded the site-specific objective. This does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy However, the minimum sample number requirements of Table 3.2 are not met.. 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 the minimum sample number requirements of the Listing Policy are not met..
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10934

LOE ID:	6188
Pollutant:	Fluoride
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 fluoride samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Average fluoride concentrations on the four sampling dates were as follows: (10/28/2001) 0.3 mg/L; (5/7/2002) 0.32 mg/L; (10/24/2002) 0.47 mg/L; and (3/20/2003) 0.17 mg/L. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for fluoride is 2 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight fluoride samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	6187
Pollutant:	Fluoride
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	2
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 fluoride samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Average fluoride concentrations on the four sampling dates were as follows: (10/28/2001) 0.3 mg/L; (5/7/2002) 0.32 mg/L; (10/24/2002) 0.47 mg/L; and (3/20/2003) 0.17 mg/L. "Annual averages" calculated from one to two datapoints per year exceeded the objective in two of three years.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The site-specific objective (in Lahontan Basin Plan Table 3-19) includes an annual average of 0.29 mg/L and a 90th percentile value of 0.38 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight fluoride samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10937
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. One line of evidence is 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. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 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 10937

LOE ID:	23517
Pollutant:	Hardness
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. Hardness was calculated for a total of 8 samples (1 to 3 per day). Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Calculated hardness values for the four sampling dates were as follows: 294, 246, 169 and 73 mg/L CaCO3/L.
Data Reference:	2007. SWAMP Data for the Antelope 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 equivalent to 0-75 mg equivalent CaCO3/L is considered "soft."
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Hardness was calculated for 8 samples (1-3 per date) collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7792
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 datapoints exceeds the aquatic life criterion or the California Maximum Contaminant Level (MCL). 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. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. None of four datapoints exceeded the aquatic life criterion or the MCL 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 7792

LOE ID:	23512
Pollutant:	Iron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 dissolved iron samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average concentrations of dissolved iron on the four sampling dates were as follows: (10/28/2001) an estimated 8 ug/L; (5/7/2002) 28 ug/L; (10/24/2002) 15 ug/L; and (3/20/2003) 60 ug/L. The criterion was not violated.
Data Reference:	2007. SWAMP Data for the Antelope 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:	One station was sampled on each sampling date.
Temporal Representation:	Eight dissolved iron samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	6198
Pollutant:	Iron
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 dissolved iron samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average concentrations of dissolved iron on the four sampling dates were as follows: (10/28/2001) an estimated 8 ug/L; (5/7/2002) 28 ug/L; (10/24/2002) 15 ug/L; and (3/20/2003) 60 ug/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Antelope 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 secondary 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:	One station was sampled on each sampling date.
Temporal Representation:	Eight dissolved iron samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10940
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. One line of evidence is available in the administrative record to assess this pollutant. There are no applicable state or federal standards or criteria for 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 do not satisfy the data quantity requirements of section 6.1.5 of the Policy. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. There are no applicable water quality standards or criteria and the data cannot be assessed using 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 there are no applicable water quality standards or criteria.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10940

LOE ID:	23514
Pollutant:	Magnesium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 samples for dissolved magnesium (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Magnesium concentrations for the four sampling dates were as follows: 17.5 mg/L, 17 mg/L, 19.6 mg/L, and 5.7 mg/L.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for dissolved magnesium.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10929
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. One line of evidence are available in the administrative record to assess this pollutant. Two of the datapoints exceed the California Maximum Contaminant Level. 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 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. Four sampling dates in three years are not enough to capture the expected seasonal and annual variability in environmental conditions and constituent concentrations. 3. Two of four datapoints exceeded the California Maximum Contaminant Level 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 the applicable standard is being exceeded, the data are not temporally representative.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10929

LOE ID:	6200
Pollutant:	Manganese
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	2
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 dissolved manganese samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average concentrations of dissolved manganese on the four sampling dates were as follows: (10/28/2001) 345 ug/L; (5/7/2002) 657 ug/L; (10/24/2002) an estimated 1.1 ug/L; and (3/20/2003) 49.4 ug/L. The MCL was violated on two of the four sampling dates. (Note: MCLs for metals are expressed as total metals. Only dissolved manganese data are available.)
Data Reference:	2007. SWAMP Data for the Antelope 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 secondary 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:	One station was sampled on each sampling date.
Temporal Representation:	Eight dissolved manganese samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10933
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 lines of evidence are available in the administrative record to assess this pollutant. None of the datapoints exceeds the California Maximum Contaminant Level. One of the annual average datapoints (based on a single sampling date) 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. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. None of 4 datapoints exceeded the MCL. One of 3 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 10933

LOE ID:	6184
Pollutant:	Nitrate
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 samples for nitrate plus nitrite as N (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Five of the eight samples (collected on three dates) were below the detection level. The average nitrate plus nitrite concentration in three samples collected on 3/20/2003 was 0.186 mg/L (as N). Samples for nitrite were collected concurrently with the nitrate plus nitrite samples. Five of the eight samples (collected on three dates) were below the detection level. The average nitrite concentration in three samples collected on 3/20/2003 was 0.005 mg/L. After subtracting the nitrite value from the nitrate value, the average nitrate concentration in the 3/20/03 sample was 0.181 mg/L as N. This is equivalent to 0.801 mg/L as nitrate, which (as the annual average datapoint for 2003) is in violation of the objective.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The site-specific objectives for nitrate (measured “as nitrate” rather than “as N”) in Lahontan Basin Plan Table 3-19 includes an annual average of 0.4 mg/L and a 90th percentile value of 0.7 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight nitrate plus nitrite samples (1-3 per date) and eight nitrite samples were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	6182
Pollutant:	Nitrate
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 samples for nitrate plus nitrite as N (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Five of the eight samples (collected on three dates) were below the detection level. The average nitrate plus nitrite concentration in three samples collected on 3/20/2003 was 0.186 mg/L. The combined value of the two pollutants did not violate the MCL for nitrate.
Data Reference:	2007. SWAMP Data for the Antelope 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 (as nitrate), equivalent to 10 mg/L as N.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight nitrate plus nitrite samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10930
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 datapoints exceeds the California Maximum Contaminant Level (MCL). 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. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. None of 4 datapoints exceeded the MCL 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 10930

LOE ID:	23508
Pollutant:	Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 nitrite samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Five of the eight samples (collected on three dates) were below the detection level. The average nitrite plus nitrate concentration in three samples collected on 3/20/2003 was 0.186 mg/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Antelope 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 is 10 mg/L (as N).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10932
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. Two lines of evidence are available in the administrative record to assess this pollutant. None of the datapoints exceeds the California Maximum Contaminant Level (MCL). No biological data are available for assessment of compliance 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. The limited sampling frequency was insufficient to document seasonal and annual variation. 3. None of 4 datapoints exceeded the MCL and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. There are no biological data available for assessment of compliance with the biostimulatory substances objective and compliance cannot be assessed using Table 3.1. 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 no biological data are available for assessment of compliance with the other standard.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10932

LOE ID:	6183
Pollutant:	Nitrite
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 nitrite samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Five of the eight samples (collected on three dates) were below the detection level. The average nitrite concentration in three samples collected on 3/20/2003 was 0.005 mg/L. No data on algae were available for assessment of compliance with the biostimulatory substances objective.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The Lahontan Basin Plan does not include a site- specific numerical objective for nitrite in Littlerock Reservoir. 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:	One station was sampled on each sampling date.
Temporal Representation:	Eight nitrite samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	6177
Pollutant:	Nitrite
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 nitrite samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Five of the eight samples (collected on three dates) were below the detection level. The average nitrite concentration in three samples collected on 3/20/2003 was 0.005 mg/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Antelope 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 (as N).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight nitrite samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7764
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. Two of the datapoints 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 Listing Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. The limited sampling frequency (one or two sampling runs per year) was insufficient to document diel, seasonal and annual variation in dissolved oxygen concentrations. 3. Dissolved oxygen concentrations in two of four composite datapoints exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. However, the minimum sample number requirements of Table 3.2 are not met. 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 the minimum sample number requirements of the Listing Policy are not met.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7764

LOE ID:	5993
Pollutant:	Oxygen, Dissolved
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	2
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. Depth profiles of dissolved oxygen, including a total 42 separate samples, were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. For dissolved oxygen, this should be the minimum value. The minimum dissolved oxygen concentrations for the four dates were 5, 0.5, 4.5 and 2.9 mg/L. Two of these values exceeded the objective.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The water quality objective is a 1 day minimum dissolved oxygen concentration is 4.0 mg/L (Lahontan Basin Plan Table 3-6).
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:
Temporal Representation:	Depth profile samples of oxygen (a total of 42 samples taken at 1 meter intervals) were collected on four separate sampling dates ( October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10938
Pollutant:	Potassium
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. There are no applicable state or federal standards or criteria for potassium. 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. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. There are no applicable water quality standards or criteria and the data cannot be assessed using 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 there are no applicable water quality standards or criteria..
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10938

LOE ID:	23515
Pollutant:	Potassium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 samples for dissolved potassium (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Potassium concentrations for the four sampling dates were as follows: 6.4 mg/L, 5.94 mg/L, 7.35 mg/L, and 3.16 mg/L.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for dissolved potassium.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7793
Pollutant:	Silica
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 3.1 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. There are no state or federal standards or criteria for silica. Only four datapoints are available for assessment. If there were applicable standards or criteria, at least five samples would be required for assessment using Listing Policy Table 3.2. Therefore, Lahontan Water Board staff's conclusion is that there is insufficient information in the record for assessment of the available data on dissolved silica. 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.
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 and the minimum sample number requirement of the Listing Policy is not met.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7793

LOE ID:	6190
Pollutant:	Silica
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 silica samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average silica concentrations on the four sampling dates were as follows: (10/28/2001) 28.1 mg/L; (5/7/2002) 16.5 mg/L; (10/24/2002) 1.4 mg/L; and (3/20/2003) 11.4 mg/L.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	There are no state or federal standards or criteria for silica (silicon dioxide) and Lahontan Water Board staff are not aware of any criteria or guidelines from the scientific literature. Silica is ecologically important as a component of the cell walls (frustules) of diatoms.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight silica samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10941
Pollutant:	Sodium
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 are available in the administrative record to assess this pollutant. Three of the datapoints exceed the USEPA drinking water advisory level for persons who must restrict their sodium intake. The USEPA emphasizes that this criterion is not to be applied to the general population.. 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. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. Three of four datapoints exceeded the USEPA criterion and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. The minimum sample number requirement of Table 3.2 was not met. 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 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 10941

LOE ID:	23516
Pollutant:	Sodium
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	4
Number of Exceedances:	3
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 samples for dissolved sodium (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Sodium concentrations for the four sampling dates were as follows: 27.1 mg/L, 30.4 mg/L, 39.8 mg/L and 10.3 mg/L.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The U.S. Environmental Protection Agency's drinking water health advisory criterion for sodium is 20 mg/L.
Objective/Criterion Reference:	What is EPA's current guidance regarding sodium in drinking water? Ground Water and Drinking Water Quality, Answer ID 1607.
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7763
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 3.1 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. However, the four available datapoints do not meet the minimum sample number requirements of Listing Policy Table 3.2. 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.The limited sampling frequency (only one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. None of 4 datapoints exceeded the California Maximum Contaminant Level and this does not exceed the allwable 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 available data do not meet the minimum sample number requirements of the Listing Policy.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7763

LOE ID:	6010
Pollutant:	Specific Conductance
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. Depth profiles of specific conductance, including a total of 42 separate measurements, were taken in the field. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Average specific conductance on each of the the four sampling dates was as follows: (10/28/2001) 606 uS/cm; (5/7/2002) 601 uS/cm; (10/24/2002) 482 uS/cm; and (3/20/2003) 191 uS/cm . The MCL was not exceeded. This assessment is based on the field data summarized above. Eight additional laboratory measurements of specific conductance were taken in samples collected on the same dates as the field samples. After averaging results for collected on the same day, the remaining laboratory values were 685, 582, 459 (estimated) and 195 uS/cm.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	California drinking water Maximum Contaminant Levels (MCLs) apply to ambient surface waters with designated MUN uses under the Lahontan Basin Plan’s water quality objective for “Chemical Constituents.” The MCL for Specific Conductance is 900 microsiemens per centimeter or uS/cm.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Depth profile samples of specific conductance (a total of 42 measurements taken at 1 meter intervals) were collected on four separate sampling dates (in October 2001, May 2002, October 2002 and March 2003). An additional eight laboratory measurements were taken for these dates.
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7794
Pollutant:	Sulfates
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 3.1 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 drinking water MCL. "Annual average" sulfate concentrations based on only one or two samples per year exceeded the site-specific water quality objective in two of three years. The three annual average datapoints did not meet the minimum sample number requirements of Listing Policy Table 3.2. 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.The limited sampling frequency (only one or two samples per year) was insufficient to document seasonal and annual variation. 3. .Two out of three annual average datapoints exceeded the site-specific objective. None of 8 samples exceeded the California Maximum Contaminant Level. The allowable frequency listed in Table 3.2 of the Listing Policy is not exceeded. 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 the drinking water MCL is not being exceeded and there is insufficient information to assess compliance with the site-specific objective.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7794

LOE ID:	6186
Pollutant:	Sulfates
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 sulfate samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average sulfate concentrations on the four sampling dates were as follows: (10/28/2001) 37.3 mg/L; (5/7/2002) 38.6 mg/L; (10/24/2002) 33.5 mg/L; and (3/20/2003) 13.4 mg/L. The MCL was not violated.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's water quality objective for "Chemical Constituents." The MCL for sulfate is 250 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight sulfate samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	6185
Pollutant:	Sulfates
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Dissolved
Beneficial Use:	Cold Freshwater Habitat
Number of Samples:	3
Number of Exceedances:	2
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 sulfate samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. .Average sulfate concentrations on the four sampling dates were as follows: (10/28/2001) 37.3 mg/L; (5/7/2002) 38.6 mg/L; (10/24/2002) 33.5 mg/L; and (3/20/2003) 13.4 mg/L. Two of three "annual averages" calculated from one or two datapoints per year, exceeded the objective.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The site-specific objective (Lahontan Basin Plan Table 3-19) includes an annual average of 16.5 mg/L and a 90th percentile value of 19.0 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight sulfate samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7762
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 once or twice a year, 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 minimum sample number requirements of the Listing Policy were not met.
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7762

LOE ID:	5140
Pollutant:	Temperature, water
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The U. S. Geological Survey took depth profile measurements of temperature in Littlerock Reservoir on four dates in 2001, 2002 and 2003. In 42 measurements, temperatures ranged from 8 to 17.5 degrees Celsius. The listing policy directs that multiple samples collected on the same date in the same location should be combined and represented by single value. Average temperatures in the depth profiles for the four sampling dates were 14. 7, 14.9, 15.2 and 8.9 degrees Celsius. (The reservoir was stratified on two dates and mixed on two dates.) Sampling frequency was inadequate to characterize the natural temperature regime, including diel, seasonal and annual variation, or to detect whether changes in violation of the objective occurred.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The applicable portions of the Lahontan Basin Plan's narrative temperature objective are as follows: "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:	Depth profile samples were collected at a single station on each date.
Temporal Representation:	Depth profile temperature measurements were taken on four different dates in 2001, 2002, and 2003. Sample numbers varied with reservoir depth on each date (from 3 to 20 samples per day).
Environmental Conditions:	Littlerock (sometimes spelled "Little Rock") Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	7795
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 3.1 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 Maximum Contaminant Level. The number of available annual average datapoints does not meet the minimum sample number requirement of Listing Policy Table 3.2. 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 quanity requirements of section 6.1.5 of the Policy. The limited sampling frequency (one or two sampling runs per year) was insufficient to document seasonal and annual variation. 3. None of the samples exceeded the California Maximum Contaminant Level. Two out of three annual average datapoints exceeded the site-specific 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 the MCL was not exceeded and the minimum sample number requirements for assessment of compliance with the site-specific objective were not met..
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 7795

LOE ID:	6205
Pollutant:	Total Dissolved Solids
LOE Subgroup:	Pollutant-Water
Matrix:	Water
Fraction:	Total Dissolved
Beneficial Use:	Municipal & Domestic Supply
Number of Samples:	4
Number of Exceedances:	0
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 TDS samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Single value or daily average TDS concentrations on the four sampling dates were as follows: (10/28/2001) 414 mg/L; (5/7/2002) 380 mg/L; (10/24/2002) 305 mg/L; and (3/20/2003) 136 mg/L Annual averages" based on one or two datapoints per year exceeded the site-specific objective in two of three years. The MCL was not exceeded.
Data Reference:	2007. SWAMP Data for the Antelope 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 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:	One station was sampled on each sampling date.
Temporal Representation:	Eight TDS samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
LOE ID:	6178
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:	2
Data and Information Type:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. A total of 8 TDS samples (1 to 3 per day) were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. Single value or daily average TDS concentrations on the four sampling dates were as follows: (10/28/2001) 414 mg/L; (5/7/2002) 380 mg/L; (10/24/2002) 305 mg/L; and (3/20/2003) 136 mg/L Annual averages" based on one or two datapoints per year exceeded the site-specific objective in two of three years.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The site-specific objective (in Lahontan Basin Plan Table 3-19) includes an annual average Total Dissolved Solids (TDS) concentration of 176 mg/L and a 90th percentile value of 180 mg/L.
Objective/Criterion Reference:	2007. Water Quality Control Plan for the Lahontan Region (as amended).
Evaluation Guideline:
Guideline Reference:
Spatial Representation:	One station was sampled on each sampling date.
Temporal Representation:	Eight TDS samples (1-3 per date) were collected on four separate dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID	10935
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. (A pH range of 6.5 to 8.5 units applies to "all other waters.") 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 the minimum sample number requirements of the Listing Policy are not met and the data are insufficient to establish baseline and trend conditions under Listing Policy section 3.10..
SWRCB Board Decision / Staff Recommendation:
USEPA Decision:

Lines of Evidence (LOEs) for Decision ID 10935

LOE ID:	5994
Pollutant:	pH
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:	Non-fixed station physical/chemical (conventional + toxicants)
Data Used to Assess Water Quality:	The USGS sampled Littlerock Reservoir under the Region 6 SWAMP program on four dates between 2001 and 2003. Depth profiles of pH, including a total of 42 separate field measurements, were taken. Section 6.1.5.6 of the Listing Policy directs that data collected at a single location on the same day should be combined and represented by a single resultant value. For pH, this should be the maximum and minimum values. The ranges of pH on the four sampling dates were as follows: (10/28/2001) 7.2 to 7.4 units; (5/7/2002) 7.5 to 8.4 units; (10/24/2002) 8.2 to 8.4 units; and (3/20/2003) 7.1 to 7.7 units. Eight laboratory measurements of pH were taken for samples collected on the same dates as the field measurements. One of these samples was an estimate. After combining data collected on the same day, the four laboratory values ranged from 7.2 to 8.0 units. Sampling frequency was inadequate to document background conditions including diel, seasonal and annual variations in pH, or to detect change if change has occurred.
Data Reference:	2007. SWAMP Data for the Antelope Hydrologic Unit.
Water Quality Objective/Criterion:	The Lahontan Basin Plan's water quality 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 was sampled on each sampling date.
Temporal Representation:	Depth profile samples of oxygen (a total of 42 samples taken at 1 meter intervals) were collected on four separate sampling dates (in October 2001, May 2002, October 2002 and March 2003).
Environmental Conditions:	Little Rock (or Littlerock) Reservoir was formed by damming Little Rock Creek. The headwaters of the creek are located in Angeles National Forest near the crest of the San Gabriel Mountains. Below the reservoir the creek flows onto the Mojave desert and becomes intermittent. The reservoir provides domestic water supply for the city of Palmdale.
QAPP Information:	The data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):