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

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name: Carson River, West Fork (Woodfords to Paynesville)
Water Body ID: CAR6331001320011213134239
Water Body Type: River & Stream
 
DECISION ID
6486
 
Pollutant: Sodium
Final Listing Decision: Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2006)
Revision Status Revised
Reason for Delisting: State determines water quality standard is being met
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: This segment was placed on the 2002 Section 303(d) list for violation of the water quality objective for "Percent Sodium." Percent Sodium is the ratio of sodium ion concentration to the sum of the concentrations of calcium, magnesium and potassium ions. It is an older irrigation water criterion and is no longer widely used.The 2002 listing was for "Sodium" rather than "Percent Sodium" because "Sodium" was the only picklist choice available in the database in use at the time.

In 2006 the Lahontan RWQCB adopted Basin Plan amendments to replace the water quality objectives for percent sodium for surface waters of the Carson and Walker River watersheds with new objectives for "Sodium Adsorption Ratio" (SAR). The amendments were approved by the SWRCB and the Office of Administrative Law in 2007 and by the USEPA, Region IX in 2008. .

SAR is a ratio of sodium ion concentration to the concentrations of calcium and magnesium ions. It is calculated differently from Percent Sodium and the two types of objectives are NOT directly comparable.

The SAR limits in the new objectives are compatible with current federal and international irrigation water quality criteria and with the State of Nevada's antidegradation- based SAR standards for state line stations. The new SAR limits are expressed as annual means, rather than means of monthly means. A single SAR objective for the West Fork Carson River in California has replaced the two objectives for Percent Sodium that were applicable to different segments of the river.

The listing for sodium is being considered for removal from the section 303(d) list under section 4 of the Listing Policy. Under this section 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. .The new SAR objective for the Headwaters to Woodfords segment of the West Fork Carson River has been attained in 19 out of 19 years.

Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for removing this water segment-pollutant combination from the section 303(d) list.

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 satisfy the data quantity requirements of section 6.1.4 of the Listing Policy.
3. The new water quality objective was attained in 19 out of 19 years and this does not exceed the allowable frequency in Table 3.2 of the Listing Policy.
4. Pursuant to section 4.11 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 be removed from the section 303(d) list because applicable water quality standards for the pollutant are not being exceeded.
 
SWRCB Board Decision / Staff Recommendation:
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 6486
 
LOE ID: 5688
 
Pollutant: Sodium
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Dissolved
 
Beneficial Use: Agricultural Supply
 
Number of Samples: 19
Number of Exceedances: 0
 
Data and Information Type: Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: Table 3 of the Region 6 staff report for the Basin Plan amendments summarizes annual average SAR values for the West Fork Carson River. Lahontan RWQCB staff calculated these averages using historical data on SAR or the component ions. For data collected by the South Tahoe Public Utility District between 1984 and 2002, annual average SAR values ranged from 0.3 to 0.4. The mean annual average value was 0.3. The water quality objective (SAR =1) was attained.
Data Reference: South Tahoe Public Utility District (PUD). Self-monitoring monthly reports from 2000 to 2003. Including Carson River and Indian Creek. South Lake Tahoe Public Utilities District. South Lake Tahoe, CA: Lahontan RWQCB
  South Tahoe Public Utility District (PUD). Self-monitoring monthly reports from 1997 to 2000. Including: Carson River and Indian Creek. South Lake Tahoe Public Utility District. South Lake Tahoe, CA: Lahontan RWQCB
  Memorandum: Summary of water quality analysis for potential CWA 303(d) listing of the lower West Fork of the Carson River. South Lake Tahoe, CA: Lahontan RWQCB
  2006. Technical Staff Report for Revised Sodium-Related Standards for the Carson and Walker River Watersheds.
 
Water Quality Objective/Criterion: The water quality objective for Sodium Adsorption Ratio (SAR) in the West Fork Carson River is a limit of 1, as an annual average. (As a ratio, SAR has no units.) The objective includes the formula for calculating SAR and natural sources exclusion language.

The approved plan amendments have not yet been physically incorporated into the text of the Basin Plan. A copy of the amendments is included in the administrative record of the 2008 Integrated Report and is used as a reference in this LOE.
Objective/Criterion Reference: 2007. Water Quality Control Plan for the Lahontan Region (as amended).
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: One station in this segment was sampled.
Temporal Representation: The data cited above were collected at approximately monthly intervals between 1984 and 2002, for 211 samples in all. Nineteen annual average calculations were done.
Environmental Conditions: The West Fork Carson River is an interstate river with headwaters near the Sierra Nevada crest and its lowest point in California in the Carson Valley. It joins the East Fork to form the Carson River in Nevada. Water from the West Fork is used for irrigation of pasture and some field crops in the Carson Valley in California, and it contributes to the irrigation supply in Nevada.
QAPP Information: The quality assurance requirements of the SWAMP QAPP were met.
QAPP Information Reference(s):
 
DECISION ID
6484
 
Pollutant: Nitrogen
Final Listing Decision: List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2006)
Revision Status Original
Sources: Agriculture-irrigation tailwater | Agriculture-storm runoff | Agriculture-subsurface drainage | Atmospheric Deposition | Channel Erosion | Erosion/Siltation | Habitat Modification | Highway Maintenance and Runoff | Natural Sources | Pasture Grazing-Riparian and/or Upland | Range Grazing-Riparian and/or Upland | Recreational and Tourism Activities (non-boating) | Removal of Riparian Vegetation | Silviculture | Streambank Modification/Destabilization | Wastewater - land disposal
Expected TMDL Completion Date: 2019
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.
 
RWQCB Board Decision / Staff Recommendation: No new data were assessed for 2008. The decision has not changed.
 
SWRCB Board Decision / Staff Recommendation: N/A
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 6484
 
LOE ID: 4599
 
Pollutant: Nitrogen
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Cold Freshwater Habitat
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Not Specified
Data Used to Assess Water Quality: Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: Placeholder reference pre-2006 303(d)
 
Water Quality Objective/Criterion: Unspecified
Objective/Criterion Reference: Placeholder reference pre-2006 303(d)
 
Evaluation Guideline: Unspecified
Guideline Reference: Placeholder reference pre-2006 303(d)
 
Spatial Representation: Unspecified
Temporal Representation: Unspecified
Environmental Conditions: Unspecified
QAPP Information: Unspecified
QAPP Information Reference(s):
 
DECISION ID
6485
 
Pollutant: Pathogens
Final Listing Decision: List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: List on 303(d) list (TMDL required list)(2006)
Revision Status Original
Sources: Agricultural Return Flows | Natural Sources | Pasture Grazing-Riparian and/or Upland | Recreational and Tourism Activities (non-boating)
Expected TMDL Completion Date: 2019
Impairment from Pollutant or Pollution: Pollutant
 
Weight of Evidence: 303(d) listing decisions made prior to 2006 were not held in an assessment database. The Regional Boards will update this decision when new data and information become available and are assessed.
 
RWQCB Board Decision / Staff Recommendation: No new data were assessed for 2008. The decision has not changed.
 
SWRCB Board Decision / Staff Recommendation: N/A
 
USEPA Decision:
 
 
Lines of Evidence (LOEs) for Decision ID 6485
 
LOE ID: 4600
 
Pollutant: Pathogens
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Not Recorded
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 0
Number of Exceedances: 0
 
Data and Information Type: Not Specified
Data Used to Assess Water Quality: Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: Placeholder reference pre-2006 303(d)
 
Water Quality Objective/Criterion: Unspecified
Objective/Criterion Reference: Placeholder reference pre-2006 303(d)
 
Evaluation Guideline: Unspecified
Guideline Reference: Placeholder reference pre-2006 303(d)
 
Spatial Representation: Unspecified
Temporal Representation: Unspecified
Environmental Conditions: Unspecified
QAPP Information: Unspecified
QAPP Information Reference(s):