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

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Mojave River (Upper Narrows to Lower Narrows)
Water Body ID:	CAR6282000020080817142158
Water Body Type:	River & Stream


DECISION ID	21579	Region 6
Mojave River (Upper Narrows to Lower Narrows)

Pollutant:	1, 1, 2-trichloro-1, 2, 2-trifluoroethane \| 1, 1-dichloroethane \| 1, 3 -dichlorobenzene \| 1, 4 -dichlorobenzene \| 1,1,1-Trichloroethane \| 1,1-Dichloroethylene (DCE)/ Vinylidene Chloride \| 1,2-Dichloroethane \| 1,2-Dichloroethylene,-trans \| 1,2-Dichloropropane \| Benzene \| Bromoform \| Carbon tetrachloride \| Chlorobenzene (mono) \| Chlorodibromomethane \| Chloroform \| Dichlorobromomethane \| Dichlorodifluoromethane \| Dichloromethane \| Diethyl ether \| Diisopropyl ether \| Ethylbenzene \| Methyl tert-pentyl ether \| Styrene \| Tert-butyl ethyl ether \| Tetrachloroethylene/PCE \| Toluene \| Trichloroethene \| Trichlorofluoromethane (CFC-11) \| Vinyl chloride \| cis-1,2-Dichloroethylene \| m-Xylene \| o-Dichlorobenzene \| o-Xylene
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 303(d) 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: These pollutants are being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. All of the samples analyzed for each of 32 pollutants were below detection levels. Per section 6.1.5.5 of the Listing Policy, the applicable standards are presumed to be attained. 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 in 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 21579, Multiple Pollutants	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6806

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 this station under the Region 6 SWAMP program between 2001 and 2005. Fifteen quarterly samples were analyzed for each of 32 organic compounds. All of these samples were below detection levels. Per Listing Policy Section 6.1.5.5., none of the applicable standards were exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The following listed organic compounds have no state or federal freshwater aquatic life standards or criteria: 1, 1, 2 trichloro, 1, 2, 2 trifluoroethane, diethyl ether, diisopropyl ether, methyl tert pentyl ether, styrene, tert butyl ethyl ether, vinyl chloride, m xylene, and o xylene. The U.S. Environmental Protection Agency (USEPA) Lowest Observed Effect Level (LOEL) criteria for other listed compounds are as follows. (Single numbers (or the first of two numbers) are the acute toxicity criteria; the second of two numbers is the chronic toxicity criterion.) 1, 1, dichloroethane, 1120 ug/L/ 763 ug/L; 1, 3 dichlorobenzene, 11,800 ug/L/ 20,000 ug/L; 1, 4 dichlorobenzene, 1120 ug/L/ 763 ug/L; 1, 1, 1 trichloroethane. 18,000 ug/L; 1, 2 dichloroethylene, 11, 600 ug/L; 1, 2 dichloroethane 11, 800 ug/L/ 20, 000 ug/L; 1, 2 dichloroethylene (trans), 11,600 ug/L; 1, 2 dichloropropane, 23,000 ug/L/ 5700 ug/L; benzene, 5300 ug/L; bromoform, 11,000 ug/L; carbon tetrachloride, 35,200 ug/L, chlorobenzene, 250 ug/L; chloroform 28,900 ug/L/ 1240 ug/L; chlorodibromomethane, 11,000 ug/L; dichlorobromomethane, 11,000 ug/L; dichloromethane, 11,000 ug/L; ethylbenzene, 32,000 ug/L; tetrachloroethylene, 5280 ug/L/840 ug/L; toluene, 17,500 ug/L; trihloroethene, 45,000 ug/L; trichlorofluoromethane, 11,000 ug/L; cis,1, 2 dichloroethylene, 11, 600 ug/L, and o-dichlorobenzene, 1120 ug/L/763 ug/L.

Objective/Criterion Reference:

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

Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River below [Mojave] Forks Reservoir, was sampled.

Temporal Representation:

Fifteen quarterly samples were analyzed for each of 32 organic compounds.

Environmental Conditions:

The mainstem Mojave River originates below the Mojave River Forks Reservoir. The reservoir was constructed by damming the rivers two major tributaries, Deep Creek and the West Fork Mojave River. The mainstem Mojave River originates below the Mojave River Forks Reservoir. The reservoir was constructed by damming the rivers two major tributaries, Deep Creek and the West Fork Mojave River. The river is intermittent and surface water is present in only a few locations. The Mojave River is designated for both the Warm Freshwater Habitat and Cold Freshwater Habitat beneficial uses.

QAPP Information:

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

QAPP Information Reference(s):

Line of Evidence (LOE) for Decision ID 21579, Multiple Pollutants	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6807

Pollutant:

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:

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

There are no applicable state or federal human health standards or criteria for the following listed chemicals: diethyl ether, diisopropyl ether, methyl tert pentyl ether, and tert butyl ethyl ether. The California Sstate Notification Level for dichlorodifluoromethane is 1000 ug/L. The California Maximum Contaminant Levels for the remaining listed organic compounds are as follows: 1, 1, 2 trichloro 1, 2, 2 trifluoroethane, 1200 ug/L; 1, 1 dichloroethane, 0.5 ug/L; 1, 3 dichlorobenzene, 600 ug/L; 1, 4 dichlorobenzene, 5 ug/L; 1, 1,1 trichloroethane, 200 ug/L; 1 2 dichloroethylene, 6 ug/L; 1, 2 dichloroethane, 0.5 ug/L; 1, 2 dichloroethylene (trans), 10 ug/L; 1, 2 dichloropropane, 5 ug/L; benzene, bromoform, 80 ug/L; chloroform, 80 ug/L; carbon tetrachloride, 0.5 ug/L; chlorobenzene (mono) 70 ug/L; chlorodibromomethane, 80 ug/L; dichlorobromomethane, 80 ug/L; dichloromethane, 5 ug/L; ethylbenzene, 300 ug/L; styrene, 100 ug/L; tetrochloroethylene, 5 ug/L; toluene, 150 ug/L; trichloroethene, 5 ug/L, trichlorofluoromethane, 150 ug/L; vinyl chloride, 0.5 ug/L, cis 1, 2 dichloroethylene, 6 ug/L; m-xylene, 1750 ug/L; o-dichlorobenzene, 600 ug/L; o-xylene, 1750 ug/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River below [Mojave] Forks Reservoir, was sampled.

Temporal Representation:

Fifteen quarterly samples were analyzed for each of 32 organic compounds.

Environmental Conditions:

The mainstem Mojave River originates below the Mojave River Forks Reservoir. The reservoir was constructed by damming the rivers two major tributaries, Deep Creek and the West Fork Mojave River. The mainstem Mojave River originates below the Mojave River Forks Reservoir. The reservoir was constructed by damming the rivers two major tributaries, Deep Creek and the West Fork Mojave River. The river is intermittent and surface water is present in only a few locations.The Mojave River is designated for both the Warm Freshwater Habitat and Cold Freshwater Habitat beneficial uses.

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	22000	Region 6
Mojave River (Upper Narrows to Lower Narrows)

Pollutant:	Boron
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 303(d) 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 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 samples exceeded the California State Notification Level criterion. None of 5 annual average datapoints exceeded the site-specific objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 22000, Boron	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

8415

Pollutant:

Boron

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Boron concentrations in 14 samples ranged from 72 to 275 ug/L. Annual average concentrations (based on 2 to 4 samples per year) ranged from 126 to 168 ug/L.The annual average objective was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective for the Mojave River at Upper Narrows station (Lahontan Basin Plan Table 3-21, Station 19) includes an annual average boron concentration of 0.2 mg/L (200 ug/L) and a 90th percentile value of 0.3 mg/L (300 ug/L).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fourteen quarterly samples (2 to 4 per year) 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 22000, Boron	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

8417

Pollutant:

Boron

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Boron concentrations in 14 samples ranged from 72 to 275 ug/L. The criterion was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The California State Notification Level criterion is 1000 ug/L.

Objective/Criterion Reference:

Compilation of Water Quality Goals

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fourteen quarterly samples (2 to 4 per year) 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	21246	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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 303(d) 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 MCL. None of five annual averages exceeded the site-specific objective, and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 21246, Chloride	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6862

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Chloride concentrations in 15 samples ranged from 20.3 to 72.3 mg/L. The annual average objective was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective for the Mojave River at Upper Narrows station (Lahontan Basin Plan Table 3-21) includes and annual average chloride concentration of 75 mg/L and a 90th percentile value of 100 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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 21246, Chloride	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6863

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:

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

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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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	21596	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) 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. One line of evidence is available in the administrative record to assess this pollutant. Four of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. Four of six samples exceeded the water quality objective for percent saturation 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 in 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 21596, Dissolved oxygen saturation	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6871

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 this station quarterly from 2003 to 2005 under the Region 6 SWAMP program. Percent saturation in 6 quarterly measurements ranged from 30 to 102 percent; 4 of the 6 measurements were below 80 percent.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The narrative objective in the Lahontan Basin Plan requires 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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Six measurements of percent saturation of dissolved oxygen were taken approximately quarterly between 2003 and 2005 (one measurement in October 2003 and 5 between April 2004 and July 2005).

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	21316	Region 6
Mojave River (Upper Narrows to Lower Narrows)

Pollutant:	Methyl Tertiary-Butyl Ether (MTBE)
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 303(d) 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 or the USEPA aquatic life criterion. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 15 samples exceeded either of the applicable standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:

Line of Evidence (LOE) for Decision ID 21316, Methyl Tertiary-Butyl Ether (MTBE)	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

25253

Pollutant:

Methyl Tertiary-Butyl Ether (MTBE)

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 MTBE at this station under the Region 6 SWAMP program. Of 15 quarterly samples, 8 were below the detection level and 5 were estimated values. MTBE concentrations in the remaining two samples were 0.2 and 0.3 ug/L. The criteria were not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The U.S. Environmental Protection Agency's national freshwater aquatic life criteria for methyl tert butyl ether (MTBE) are an acute value of 151, 000 ug/L and a chronic value of 51,000 ug/L.

Objective/Criterion Reference:

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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 21316, Methyl Tertiary-Butyl Ether (MTBE)	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6808

Pollutant:

Methyl Tertiary-Butyl Ether (MTBE)

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:

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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 primary MCL for MTBE is 0.013 mg/L (13 ug/L). The secondary MCL is 0.005 mg/L (5 ug/L).

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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	21635	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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 303(d) 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 exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 15 samples exceeded the applicable water quality objectives 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 in 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 21635, Nitrate	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6879

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Nitrate was calculated from available data for nitrate and "nitrate plus nitrite". Calculated nitrate concentrations in 15 samples ranged from 0.2 to 1.103 mg/L, expressed "as N." The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) were collected for nitrite and for nitrate plus nitrite 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 21635, Nitrate	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6880

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Nitrate "as N" was calculated from available data for nitrate and "nitrate plus nitrite". Calculated nitrate concentrations in 15 samples ranged from an estimated 0.2 to 1.103 mg/L expressed "as N." Expressed "as nitrate" the maximum value is 4.96 mg/L. The objective was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The objective for the West Fork Mojave River (at Lower Narrows) in Lahontan Basin Plan Table 3-20 applies upstream through the Tributary Rule. This objective is a maximum of 6 mg/L nitrate "as nitrate."

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) were collected for nitrite and for nitrate plus nitrite 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	21261	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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 303(d) 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 of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the California Maximum Contaminant Level. No biological data are available for assessment of compliance with the water quality objective for biostimulatory substances. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 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 samples exceeded the California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. No biological data are available for assessment of compliance with the objective for biostimulatory substances. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 21261, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

8381

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 this station between 2001 and 2005. Concentrations of nitrate plus nitrite in 15 quarterly samples ranged from 0.2 to 1.12 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteeen quarterly samples (2 to 4 per year) 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 21261, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6885

Pollutant:

Nitrate/Nitrite (Nitrite + Nitrate as N)

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 this station between 2001 and 2005. Concentrations of nitrate plus nitrite in 15 quarterly samples ranged from 0.2 to 1.12 mg/L. No data on algae or macrophytes are available for use in assessment of compliance with the biostimulatory substances objective.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan does not include site-specific numerical objectives for "nitrate plus nitrite" for the Mojave River. The regionwide narrative objective for biostimulatory substances states:

Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteeen quarterly samples (2 to 4 per year) 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	21605	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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 303(d) 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 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 15 samples exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 21605, Nitrite	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6877

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Two of 15 samples for NO2-N were below the detection level, and one was an estimated value. Nitrite concentrations in the remaining samples ranged from 0.005 to 0.018 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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	21247	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) 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. One line of evidence is available in the administrative record to assess this pollutant. Two of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region. 3. Two of fourteen samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 21247, Oxygen, Dissolved	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6870

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. The range of dissolved oxygen concentrations in 14 samples was 2.5 to 8.9 mg/L. Two samples were below the 4 mg/L minimum concentration.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The applicable water quality objective from Lahontan Basin Plan Table 3-6 is a one-day minimum of 4 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fourteen quarterly samples (2 to 4 per year) 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	21325	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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 303(d) 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. There are no site-specific water quality objectives for phosphorus applicable to this station. No data on algae or macrophytes are available for assessment of compliance with the 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 available data for phosphate do not satisfy the data quantity requirement of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. There are no data on algae or macrophytes available for evaluation of compliance with the applicable objective. 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 in 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 21325, Phosphate	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6883

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 this station under the Region 6 SWAMP program between 2003 and 2005. Concentrations of filtered orthophosphate as P in 6 samples ranged from 0.013 to 0.052 mg/L. No data on algae or macrophytes are available for use in assessment of compliance with the biostimulatory substances objective.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan does not include site-specific numerical objectives for phosphorus for the Mojave River. The regionwide narrative objective for biostimulatory substances states:

"Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Six quarterly samples (1 to 4 per year) were collected between 2003 and 2005.

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	21090	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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 303(d) 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. There is no site-specific water quality objective for phosphorus applicable to this station, and no data on algae or macrophytes are available for assessment of compliance with the 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 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 for total phoshorus 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 data on algae or macrophytes are available for assessment of compliance with the biostimulatory substances objective. 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 in 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 21090, Phosphorus	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6882

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 this station under the Region 6 SWAMP program between 2002 and 2005. Concentrations of total phosphorus in 11 quarterly samples ranged from 0.048 to 0.125 mg/L. Two samples were estimated values. No data on algae or macrophytes are available for use in assessment of compliance with the biostimulatory substances objective.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Eleven quarterly samples (2 to 4 per year) 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	21595	Region 6
Mojave River (Upper Narrows to Lower Narrows)

Pollutant:	Specific Conductance
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 303(d) 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. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and dissolved ion concentrations in streams of the Lahontan Region. 3. None of 15 field measurements of specific conductance exceeded the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 21595, Specific Conductance	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6873

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Specific conductance in 15 field measurements measurements ranged from 322 to 832 uS/cm. Specific conductance in an additional laboratory measurement was 485 uS/cm. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly field measurements (2 to 4 per year) were collected between 2001 and 2005. One laboratory measurement was done on a water sample collected on March 19, 2003.

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	21829	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) 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 temperature objective is an antidegradation-based objective that requires that there be no change in temperature in waters designated for the Cold Freshwater Habitat (COLD) beneficial use. The objective does not include specific numerical limits for protection of the COLD use. Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects. One line of evidence is available to support this decision. There are not enough temperature samples to establish baseline conditions (including diel, seasonal, annual and interannual variations in temperature) or to detect declining trends in the temperature regime if such trends exist. Because temperature samples were collected only quarterly, weekly and monthly average data are not available for comparison with guidelines in the scientific literature for the temperature requirements of sensitive aquatic species such as salmonids, as directed in Listing Policy Section 6.1.5.9.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 21829, Temperature, water	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6872

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Fifteen water temperature measurements ranged from 9 to 22.5 degrees Celsius.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The applicable language from the Lahontan Basin Plan's water quality objective is as follows: "The natural receiving water temperature of al l waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses.

For waters designated WARM, water temperature shall not be altered by more than five degrees Fahrenheit ... above or below the natural temperature. For waters designated COLD, the temperature shall not be altered."

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly measurements of water temperature 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	21606	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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 303(d) 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. There is no site-specific water quality objective for Total Kjeldahl Nitrogen (TKN), and no data are available on algae or macrophytes to facilitate assessment of compliance with the objective for "biostimlatory 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.There are no data on algae or macrophytes available for assessment of compliance with the biostimulatory substances objective. 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 in 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 21606, Total Kjeldahl Nitrogen (TKN)	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6884

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 this station between 2002 and 2005. Concentrations of TKN in 11 quarterly samples ranged from 0.15 to 0.71 mg/L. No data on algae or macrophytes are available for use in assessment of compliance with the biostimulatory substances objective.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan does not include site-specific numerical objectives for Total Kjeldahl Nitrogen (TKN) for the Mojave River. The regionwide narrative objective for biostimulatory substances states:

"Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Eleven quarterly samples (2 to 4 per year) were collected between 2002 and 2005.

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	21873	Region 6
Mojave River (Upper Narrows to Lower Narrows)

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	Original
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) 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 pH objective is an antidegradation-based objective that requires that there be no change greater than 0.5 pH units in waters designated for the Cold Freshwater Habitat (COLD) or Warm Freshwater Habitat beneficial uses. Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects. One line of evidence is available to support this decision. There are not enough pH samples to establish baseline conditions (including diel, seasonal, annual and interannual variations) or to detect changes in the pH regime due to controllable factors, if such trends exist.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 21873, pH	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6886

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Field pH values in 15 measurements ranged from 7.1 to 7.9 units. An additional laboratory measurement on March 19, 2003 was 7.7 units.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's objective for pH states: "In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units.

The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis."

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly pH measurements (2 to 4 per year) were taken between 2001 and 2005. An additional laboratory measurement was taken on March 19, 2003.

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	28385	Region 6
Mojave River (Upper Narrows to Lower Narrows)

Pollutant:	Fluoride
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)(2010)
Revision Status	Original
Sources:	Natural Sources
Expected TMDL Completion Date:	2021
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) 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. Five annual average datapoints exceed the site-specific objective. None of the samples exceed the California Maximum Contaminant Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. Five of five annual average datapoints exceed the site-specific objective and this exceeds 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 in 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 28385, Fluoride	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6864

Pollutant:

Fluoride

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Chloride concentrations in 14 samples ranged from 0.3 to 0.6 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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 fluoride is 2 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fourteen quarterly samples (2 to 4 per year) 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 28385, Fluoride	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6865

Pollutant:

Fluoride

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 this station quarterly from 2001 to 2005 (2 to 4 samples per year) under the Region 6 SWAMP program. Fluoride concentrations in 14 quarterly samples ranged from 0.3 to 0.6 mg/L. Annual average concentrations ranged from 0.35 to 0.50 mg/L.The annual average objective was exceeded in five out of five years.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective from Basin Plan Table 3-21 (for Station 19) includes an annual average fluoride concentration of 0.2 mg/L and a 90th percentile value of 0 1.5 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

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

Environmental Conditions:

The mainstem Mojave River originates below the Mojave River Forks Reservoir. The reservoir was constructed by damming the rivers two major tributaries, Deep Creek and the West Fork Mojave River. The river is intermittent and surface water is present in only a few locations. Fluoride at this station probably comes from natural geothermal sources.

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	30323	Region 6
Mojave River (Upper Narrows to Lower Narrows)

Pollutant:	Sulfates
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)(2010)
Revision Status	Original
Sources:	Natural Sources \| Nonpoint Source
Expected TMDL Completion Date:	2021
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) 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: Regional Board 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. None of the samples exceeds the California Maximum Contaminant Level (MCL). Five annual average datapoints exceed the site-specific water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of fifteen samples exceeds the MCL and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. Five of five annual average datapoints exceeded the site-specific water quality objective and this exceeds the allowable frequency listed in Table 3.2. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. State Board Review and Conclusion: The April 19, 2010 State Water Board staff report for the 2010 Integrated Report recommended to place this water body on the 303(d) list for sulfates based on the State Water Board staff determination that the data were collected over a broad period of time to meet section 6.1.5.3 of the Listing Policy. The State Water Board recommendation is based on the following: Lahontan Regional Board staff had decided not to list this water body because staff thought it had insufficient information to make a decision to list. However, State Board staff finds there are 5 samples to make a decision and this meets the sample size requirements of Table 3.2 of the Listing Policy. State Water Board staff re-evaluated the available data and the recommendation has been revised. On August 4, 2010 the State Water Board approved the staff recommendation to place this water body-pollutant combination on the 303(d) list. The final language for the recommendation is: Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of fifteen samples exceeds the MCL and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. Five of five annual average datapoints exceeded the site-specific water quality objective and this exceeds the allowable frequency listed in Table 3.2. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

Regional Board Staff Decision Recommendation:	No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in 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 30323, Sulfates	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6867

Pollutant:

Sulfates

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Sulfate concentrations in 15 individual samples ranged from 22.2 to 85.6 mg/L. Annual averages (based on 2 to 4 samples per year) ranged from 42.8 to 53.4 mg/L. The annual average objective was exceeded in five out of five years.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site-specific objective from Lahontan Basin Plan Table 3-21 includes an annual average of 40 mg/L sulfate and a 90th percentile value of 100 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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 30323, Sulfates	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6866

Pollutant:

Sulfates

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. Sulfate concentrations in 15 samples ranged from 22.2 to 85.6 mg/L. The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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 sulfate 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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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	30022	Region 6
Mojave River (Upper Narrows to Lower Narrows)

Pollutant:	Total Dissolved Solids
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)(2010)
Revision Status	Original
Sources:	Source Unknown
Expected TMDL Completion Date:	2021
Impairment from Pollutant or Pollution:	Pollutant

Regional Board Staff Conclusion:	Regional Board Conclusion: This pollutant was considered for placement on the section 303(d) 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: Regional Board 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. None of the samples exceeds the California Maximum Contaminant Level (MCL). Fourteen of 15 samples exceed the site-specific water quality objective, which is a maximum value. However, listing is not recommended because the data are not temporally representative. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. Fourteen of 15 samples exceed the site-specific water quality objective and this exceeds 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. State Board Review and Conclusion: The April 19, 2010 State Water Board staff report for the 2010 Integrated Report recommended to place this water body on the 303(d) list for total dissolved solids based on the State Water Board staff determination that the data were collected over a broad period of time to meet section 6.1.5.3 of the Listing Policy. The State Water Board recommendation is based on the following: Lahontan Regional Board staff had decided not to list this water body because staff thought it had insufficient information to make a decision to list. However, State Board staff finds there are 15 samples to make a decision and this meets the sample size requirements of Table 3.2 of the Listing Policy. State Water Board staff re-evaluated the available data and the recommendation has been revised. On August 4, 2010 the State Water Board approved the staff recommendation to place this water body-pollutant combination on the 303(d) list. The final language for the recommendation is: Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. Fourteen of 15 samples exceed the site-specific water quality objective and this exceeds 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 in 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 30022, Total Dissolved Solids	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6868

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. The TDS concentrations in 15 samples ranged from 197 to 496 mg/L.The MCL was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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 recommended 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, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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 30022, Total Dissolved Solids	Region 6
Mojave River (Upper Narrows to Lower Narrows)

LOE ID:

6869

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 this station quarterly from 2001 to 2005 under the Region 6 SWAMP program. The TDS concentrations in 15 samples ranged from 197 to 496 mg/L. Fourteen of 15 samples exceeded the maximum value objective.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The site- specific objective for Total Dissolved Solids (TDS) in the West Fork Mojave River (at Lower Narrows) in Lahontan Basin Plan Table 3-20 applies upstream to this station through the Tributary Rule. This objective is a maximum of 312 mg/L.

Objective/Criterion Reference:

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

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

One station, Mojave River at Upper Narrows, was sampled.

Temporal Representation:

Fifteen quarterly samples (2 to 4 per year) 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):