Draft California 2012 Integrated Report( 303(d) List/305(b) Report)

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Rock Creek (tributary to Owens River)
Water Body ID:	CAR6032014020070824170608
Water Body Type:	River & Stream


DECISION ID	30372	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Total Dissolved Solids
Final Listing Decision:	Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	List on 303(d) list (TMDL required list)(2010)
Revision Status	Revised
Sources:	Source Unknown
Expected TMDL Completion Date:	2025
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	This pollutant is being considered for removal from the section 303(d) list under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess pollutant. Six of samples exceed the water quality objective. For LOE ID #s: 5645 and 5648, the same samples were evaluated for two beneficial uses (COLD and MUN) and so therefore should not be evaluated as independent samples, although different objectives are applied. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against 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 satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Six of 22 (although not all samples independent from one another [2010]) samples exceeded the objectives and this exceeds the allowable frequency listed in Table 4.1 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 met.

Regional Board Staff Decision Recommendation:	After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be removed from the section 303(d) list because applicable water quality standards for the pollutant are being exceeded.

Line of Evidence (LOE) for Decision ID 30372, Total Dissolved Solids	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5645

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Concentrations of TDS in 16 quarterly samples (2 to 4 samples per year) ranged from 18 to 47 mg/L. The annual average objective was exceeded in 5 of 5 years.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective for Total Dissolved Solids (TDS) in Lahontan Basin Plan Table 3-17, includes an annual average of 21 mg/L and a 90th percentile value of 23 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly samples (2 to 4 per year) were collected between 2001 and 2005..

Environmental Conditions:

Rock Creek is a tributary of the Owens River, originating near the Sierra Nevada crest. Water from the lower reach of the creek is diverted into the Los Angeles Aqueduct. In addition to the Cold Freshwater Habitat beneficial use, Rock Creek is designated for the Spawning, Reproduction and Development use.

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 30372, Total Dissolved Solids	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

33113

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

The annual average for TDS during year 2007 exceeded the Water Quality Objective.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-pecific objective for Total Dissolved Solids (TDS) in the Lahontan Basin Plan Table 3-17, includes an annual average of 21 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected from station 603RCK002 - Rock Cr, above diversion.

Temporal Representation:

Samples were collected monthly between August and December 2007

Environmental Conditions:

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 30372, Total Dissolved Solids	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5648

Pollutant:

Total Dissolved Solids

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. TDS concentrations in 16 samples ranged from 18 to 47 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

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:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly samples were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	22879	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Dissolved oxygen saturation
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	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. Two of the samples exceed the water quality objective. Although these LOEs are evaluated under different fractions, they are evaluated under the same criteria, making it applicable to combine the data. Although there are two exceedences for LOE ID # 44399, the data was only collected 8/16/2007-12/13/2007. This data is not temporally representative for this waterbody and so more data is necessary to determine impairment. 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 satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Two of eight samples exceeded the 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.

Regional Board Staff Decision 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.

Line of Evidence (LOE) for Decision ID 22879, Dissolved oxygen saturation	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

44399

Pollutant:

Dissolved oxygen saturation

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP data for Rock Creek (tributary to Owens River) to determine beneficial use support and results are as follows: 2 of 4 samples exceed the criterion for Oxygen, Saturation.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Rock Creek (tributary to Owens River) was collected at 1 monitoring site [ Rock Cr, above diversion]

Temporal Representation:

Data was collected over the time period 8/16/2007-12/13/2007.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 22879, Dissolved oxygen saturation	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21416

Pollutant:

Dissolved oxygen saturation

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2004 and 2005. In four quarterly samples, percent saturation of dissolved oxygen ranged from 91 to 102 percent. The objective was not violated.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's narrative objective states that percent saturation shall not be depressed by more than 10 percent and minimum dissolved oxygen concentration shall not be less than 80 percent saturation.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Four quarterly samples were collected between October 2004 and August 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	21068	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Fecal Coliform
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of nine samples exceeded the objective for REC-1 beneficial use; zero of four samples exceeded the objective for MUN beneficial use 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.

Regional Board Staff Decision 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.

Line of Evidence (LOE) for Decision ID 21068, Fecal Coliform	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5707

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Water column surveys (e.g. fecal coliform)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled fecal coliform bacteria quarterly at Rock Creek under the Region 6 SWAMP program between July 2004 and August 2005. Bacteria counts in four of five samples were estimated values, and the fifth sample was below the detection level.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock wastes. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected as evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Five quarterly samples were collected between July 2004 and August 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 21068, Fecal Coliform	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

34857

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Zero of the four samples exceeded the fecal coliform objective.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml. Water Quality Control Plan for the Lahontan Region.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected from station 603RCK002 - Rock Cr, above diversion.

Temporal Representation:

The samples were collected once a month from September to December 2007.

Environmental Conditions:

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 21068, Fecal Coliform	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5706

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Water column surveys (e.g. fecal coliform)

Data Used to Assess Water Quality:

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Five quarterly samples were collected between July 2004 and August 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 21068, Fecal Coliform	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

32251

Pollutant:

Fecal Coliform

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Water Contact Recreation

Number of Samples:

Number of Exceedances:

Data and Information Type:

Not Specified

Data Used to Assess Water Quality:

Zero of the four samples exceeded the Fecal Coliform objective.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The fecal coliform concentration shall not exceed more than 40/100 ml.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected from station 603RCK002 - Rock Cr, above diversion.

Temporal Representation:

The samples were collected once a month from September to December 2007.

Environmental Conditions:

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	22831	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Oxygen, Dissolved
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	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. One of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of 20 samples exceeded the 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.

Regional Board Staff Decision 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.

Line of Evidence (LOE) for Decision ID 22831, Oxygen, Dissolved	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

32269

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Zero samples were below the 1 day minimum.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The objective from Lahontan Basin Plan Table 3-6 with both cold and spawn beneficial uses shall not be less than a one-day minimum dissolved oxygen concentration of 8 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected from station 603RCK002 - Rock Cr, above diversion.

Temporal Representation:

Samples were collected between August and December 2007

Environmental Conditions:

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 22831, Oxygen, Dissolved	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21415

Pollutant:

Oxygen, Dissolved

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Concentrations of dissolved oxygen in 15 quarterly samples ranged from 7.8 to 8.2 mg/L. One sample (at 7.8 mg/L) was below the minimum concentration in the objective.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The objective (from Lahontan Basin Plan Table 3-6) is a 1-day minimum dissolved oxygen concentration of 8 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Fifteen quarterly samples were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	32259	Region 6
Rock Creek (tributary to Owens River)

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

Regional Board Staff Conclusion:	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. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 25 samples exceeded the criteria 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.

Regional Board Staff Decision 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.

Line of Evidence (LOE) for Decision ID 32259, Specific Conductance	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5643

Pollutant:

Specific Conductance

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Specific conductance in 16 field measurements ranged from 21 to 55 uS/cm. One laboratory measurement was taken for a sample collected in July 2003; it had a specific conductance of 10 uS/cm. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for specific conductance is 900 microsiemens per centimeter (uS/cm).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly field measurements of specific conductance were taken between 2001 and 2005. One laboratory measurement was taken for a sample collected in July 2003.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 32259, Specific Conductance	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

44379

Pollutant:

Specific Conductance

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP data for Rock Creek (tributary to Owens River) to determine beneficial use support and results are as follows: 0 of 9 samples exceed the criterion for Conductivity(Us).

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California Secondary MCL that is incorporated by reference in the Water Quality Control Plan, Lahontan Region for specific conductance is 900 uS/cm (Water Quality Control Plan, Lahontan Region).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

Data for this line of evidence for Rock Creek (tributary to Owens River) was collected at 1 monitoring site [ Rock Cr, above diversion]

Temporal Representation:

Data was collected over the time period 8/16/2007-12/13/2007.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)


DECISION ID	20797	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Temperature, water
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	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. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 21 samples exceeded the 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.

Regional Board Staff Decision 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.

Line of Evidence (LOE) for Decision ID 20797, Temperature, water	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

44136

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

Water Board staff assessed SWAMP data for Rock Creek (tributary to Owens River) to determine beneficial use support and results are as follows: 0 of 5 samples exceed the criterion for Water Temperature.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Water Quality Control Plan for the Lahontan Region's water quality objective for all surface waters states the following: 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 COLD, the temperature shall not be altered.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).

Guideline Reference:

Fish introductions in CA: History and impact on native fishes. Davis, CA: University of CA, Davis

Spatial Representation:

Data for this line of evidence for Rock Creek (tributary to Owens River) was collected at 1 monitoring site [ Rock Cr, above diversion]

Temporal Representation:

Data was collected over the time period 8/16/2007-12/13/2007.

Environmental Conditions:

Staff is not aware of any special conditions that might affect interpretation of the data.

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 20797, Temperature, water	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5650

Pollutant:

Temperature, water

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Sixteen water temperature measurements ranged from 0 to 16 degrees Celsius.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The relevant language from the Lahontan Basin Plan's temperature objective states: "The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction fo 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.

Temperature objectives for COLD interstate waters and WARM interstate waters are as specified in the Water Quality Control Plan for Control of Temperature in The Coastal and Interstate Waters and Encosed Bays and Estuaries of California including any revisions."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen measurements of water temperature were taken approximately quarterly between 2001 and 2005. .

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	22231	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	pH
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Revised
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	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. Zero of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Zero of 15 samples exceeded the 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.

Regional Board Staff Decision 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.

Line of Evidence (LOE) for Decision ID 22231, pH	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

33112

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

PHYSICAL/CHEMICAL MONITORING

Data Used to Assess Water Quality:

There were 5 samples with pH ranging from 7.4 to 7.8. The normal ambient pH level for this water body is unknown and so it is unknown whether any exceedences occurred.

Data Reference:

RWB6 Trend Monitoring CY2006 CY2007

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The applicable objective 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." (Lahontan Basin Plan).

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

The samples were collected from station 603RCK002 - Rock Cr, above diversion.

Temporal Representation:

Samples were collected monthly between August and December 2007

Environmental Conditions:

QAPP Information:

2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program

QAPP Information Reference(s):

Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

Line of Evidence (LOE) for Decision ID 22231, pH	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5636

Pollutant:

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. The pH values in 15 field measurements ranged from 7 to 8 units. The objective was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide 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:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Fifteen quarterly pH measurements were taken between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	21217	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Chloride
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable water quality objectives. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 15 individual samples exceeded the Maximum Contaminant level. None of five annual average datapoints exceeded the annual average 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.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21217, Chloride	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5631

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Of 15 chloride samples, 3 were estimates or below detection levels. Chloride concentrations in the remaining 12 samples ranged from 0.32 to 0.6 mg/L. The annual average objective was not exceeded during the five years of sampling.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective, in Lahontan Basin Plan Table 3-17, includes an annual average of 1.2 mg/L and a 90th percentile value of 2.0 mg/L

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Fifteen quarterly samples were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 21217, Chloride	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5635

Pollutant:

Chloride

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

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:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Fifteen quarterly samples were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	22684	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Nitrate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceeds the California Maximum Contaminant Level (MCL). None of the annual average datapoints exceeds the site-specific objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 16 samples exceeded the MCL. None of 5 annual average datapoints exceeded the site-specific objective. This does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22684, Nitrate	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21434

Pollutant:

Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Sixteen quarterly samples each were collected for nitrite and nitrite plus nitrate. Due to large numbers of below deteciton level values, numerical nitrate concentrations could not be calculated for 8 of 16 samples. Concentrations of nitrate as N in the remaining 8 samples ranged from 0.002 to 0.039 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrate is 45 mg/L expressed "as nitrate", equivalent to 10 mg/L expressed "as N."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly samples each for nitrite and nitrite plus nitrate were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 22684, Nitrate	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21429

Pollutant:

Nitrate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Sixteen samples each were collected for nitrite and nitrite plus nitrate. Due to large numbers of below detection level values, numerical nitrate concentrations could be calculated only for samples taken between October 2003 and August 2005. Concentrations of nitrate as N in 8 quarterly samples ranged from 0.002 to 0.039 mg/L. Annual average concentrations of nitrate as nitrate were estimates or below detection level for 2001, 2002 and 2003. The averages for 2004 and 2005 were 0.050 and 0.120 mg/L as nitrate. The objective was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective for nitrate (as nitrate) in Rock Creek, from Lahontan Basin Plan Table 3-17, includes an annual average of 0.3 mg/L and a 90th percentile value of 0.5 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly samples each for nitrite and nitrite plus nitrate were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	22839	Region 6
Rock Creek (tributary to Owens River)

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:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the 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. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 16 samples 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.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22839, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21414

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Seven of 16 quarterly samples for nitrite plus nitrate were below the detection level. Concentrations of nitrite plus nitrate in the remaining samples ranged from 0.001 to 0.039 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

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..

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly samples were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	22943	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Nitrite
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the 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. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 16 samples 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.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22943, Nitrite	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21413

Pollutant:

Nitrite

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Eight of 16 quarterly samples for nitrite were below the detection level. All of the 8 remaining samples had nitrite concentrations of 0.001 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrite is 1 mg/L..

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly samples were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	28523	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Phosphate
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the annual average datapoints exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 4 annual average datapoints exceeded the water quality 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.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 28523, Phosphate	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5637

Pollutant:

Phosphate

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Dissolved

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2002 and 2005. Fourteen samples were collected for PO4 as P. Six of these samples were below the detection level; the remainder ranged from 0.001 to 0.006 mg/L. Calculated total orthophosphate values for 8 samples collected between 2003 and 2005 ranged from 0.003 to 0.018 mg/L. Annual averages could not be computed for 2002 and 2003 due to the below detection level values. The annual averages for 2003 to 2004, based on 4 and 3 samples per year, were 0.0045 and 0.005 mg/L. The objective was not exceeded.

One additional sample collected in November 2001 was analyzed for hydrolyzable phosphorus and phosphate; the result was below the detection level.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective, in Lahontan Basin Plan Table 3-17, for dissolved orthophosphate includes an annual average of 0.01 mg/L and a 90th percentile value of 0.01 mg/L.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Fourteen quarterly samples for PO4 as P were collected between 2002 and 2005. Eight calculations were done for orthophosphate. One sample for hydrolyzable phosphorus plus phosphate was taken on November 27, 2001.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	22774	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Phosphorus
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. No biological data are available for assessment whether any of the chemical samples exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used do not satisfy the data quality requirements of section 6.1.4 of the Policy due to an error in the SWAMP QAPP regarding holding times for total phosphorus samples. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. No biological data are available for assessment of compliance with the objective, and the chemical data cannot be assessed using Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22774, Phosphorus	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21419

Pollutant:

Phosphorus

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2002 and 2005. Concentrations of total phosphorus in 12 quarterly samples ranged from 0.004 to 0.016 mg/L.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan does not include a site-specific objective (SSO) for total phosphorus in Rock Creek. The 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:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Twelve quarterly samples were collected between 2002 and 2005.

Environmental Conditions:

QAPP Information:

Sampling and analysis were done according to the SWAMP QAPP. However, in July 2009 an error was discovered in the QAPP related to holding times for total phosphorus samples that affects the validity of data for the Lahontan Region The holding time for samples that are not acid-preserved.should be 48 hours rather than 28 days as indicated in the QAPP. "Low level" phosphorus analyses, without acid preservation, are used in the Lahontan Region's SWAMP program. .

QAPP Information Reference(s):


DECISION ID	28255	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Sediment
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: The Lahontan Basin Plan's narrative water quality objective is an antidegradation based objective that provides that there shall be no increases in suspended sediment concentrations or loads. This pollutant is being considered for placement on the section 303(d) list under section 3.10 of the Listing Policy, which deals with trends in water quality. One line of evidence, based on quarterly sampling, is available in the administrative record to assess this pollutant. Suspended sediment concentrations and loads are dependent on flows and can change rapidly over a short time during storm or snowmelt runoff events. Quarterly samples are insufficient to capture these short term events and therefore are insufficient to define natural background suspended sediment concentrations and loads, or to detect trends. Listing Policy Section 3.10 requires that natural background conditions be established. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. Sampling frequency was insufficient to establish natural background conditions and therefore does not meet the requirements of Listing Policy section 3.10. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 28255, Sediment	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21420

Pollutant:

Sediment

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Suspended sediment concentrations in 15 quarterly samples ranged from below the detection level (in one sample) to 6 mg/L. Concurrent flow (instantaneous discharge) measurements ranged from 6.2 to 50 cubic feet per second. Suspended sediment loads were calculated for 9 samples collected between 2003 and 2005; loads ranged from below the detection level to 0.45 tons per day.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's narrative objective states: "The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect the water for beneficial uses."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Fifteen quarterly samples were collected between 2001 and 2005. Nine load calculations were done.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	23042	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Total Kjeldahl Nitrogen (TKN)
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. No biological data are available for assessment whether the chemical samples comply with the water quality objective for biostimulatory substances. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. No biological data are available for assessment of compliance with the water quality objective and the chemical samples cannot be assessed using Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 23042, Total Kjeldahl Nitrogen (TKN)	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21417

Pollutant:

Total Kjeldahl Nitrogen (TKN)

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Concentrations of total Kjeldahl nitrogen in 3 of 16 quarterly samples were estimated values. Concentrations in the remaining samples ranged from 0.06 to 0.18 mg/L.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan does not include a site-specific objective (SSO) for total Kjeldahl nitrogen (TKN) in Rock Creek. The 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:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Sixteen quarterly samples were collected between 2001 and 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	20880	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Total Nitrogen as N
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the annual average datapoints exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of the annual average datapoints exceeded the water quality 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.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20880, Total Nitrogen as N	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21418

Pollutant:

Total Nitrogen as N

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

Total

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between 2001 and 2005. Total nitrogen was calculated from its constituents for 8 quarterly samples collected between October 2003 and August 2005.
Concentrations of total nitrogen ranged from 0.088 to 0.168 mg/L. The annual average objective was not exceeded.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective, in Lahontan Basin Plan Table 3-17, includes an annual average of 0.4 mg/L and a 90th percentile value of 0.7 mg/L

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Total nitrogen was calculated for 8 samples from constituents sampled quarterly between October 2003 and August 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):


DECISION ID	22903	Region 6
Rock Creek (tributary to Owens River)

Pollutant:	Turbidity
Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision:	Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. One of the samples measured as NTU exceeds the California Maximum Contaminant Level (MCL). Compliance with the MCL cannot be determined for samples measured as NTRU. The Lahontan Basin Plan's narrative turbidity objective is non-degradation based and the turbidity data are insufficient to establish baseline conditions and detect trends as required under Listing Policy section 3.10. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the diel, seasonal and annual variability expected in streamflows and turbidity values in streams of the Lahontan Region. 3. One of four samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. (The minimum sample number requirements of Table 3.2 are not met.) The limited data do not meet the requirements of Section 3.10 for assessment of baseline and trend conditions. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22903, Turbidity	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5656

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between October 2004 and August 2005. Four turbidity measurements expressed as NTRU were all below the detection level.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU. There are no human health standards or criteria for turbidity expressed as NTRU.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Four quarterly turbidity measurements expressed as NTRU were taken between October 2004 and August 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 22903, Turbidity	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21424

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Municipal & Domestic Supply

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between October 2003 and July 2004. Three of four quarterly turbidity measurements were below the detection level ; the remaining value was 5.2 NTU, slightly above the MCL.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU.

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Four quarterly turbidity measurements expressed as NTU were taken between October 2003 and July 2004.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 22903, Turbidity	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

21423

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between October 2003 and July 2004. Three of four turbidity measurements expressed as NTU were below the detection level; the fourth was 5.2 NTU.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide turbidity objective states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Four quarterly turbidity measurements expressed as NTU were taken between October 2003 and July 2004.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 22903, Turbidity	Region 6
Rock Creek (tributary to Owens River)

LOE ID:

5653

Pollutant:

Turbidity

LOE Subgroup:

Pollutant-Water

Matrix:

Water

Fraction:

None

Beneficial Use:

Cold Freshwater Habitat

Number of Samples:

Number of Exceedances:

Data and Information Type:

Fixed station physical/chemical (conventional plus toxic pollutants)

Data Used to Assess Water Quality:

The U.S. Geological Survey sampled Rock Creek under the Region 6 SWAMP program between October 2004 and August 2005. Four quarterly turbidity measurements expressed as NTRU were all below the detection level.

Data Reference:

2007. SWAMP Data for the Owens Hydrologic Unit

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

Objective/Criterion Reference:

Water Quality Control Plan for the Lahontan Region (as amended)

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Rock Creek above Diversion, was sampled.

Temporal Representation:

Four quarterly turbidity measurements expressed as NTRU were taken between October 2004 and August 2005.

Environmental Conditions:

QAPP Information:

The data meet the quality assurance requirements of the SWAMP QAPP.

QAPP Information Reference(s):