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

Supporting Information

Regional Board 6 - Lahontan Region

Water Body Name:	Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)
Water Body ID:	CAR6282000020080816195148
Water Body Type:	River & Stream


DECISION ID	21454	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 Tertiary-Butyl Ether (MTBE) \| 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 15 samples analyzed for each of 33 different organic pollutants were below detection levels. Per Listing Policy 6.1.5.5., 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 21454, Multiple Pollutants	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6800

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 collected for each of 33 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) acute and chronic freshwater aquatic life criteria for methyl tert butyl ether (MTBE) are 151,000 and 51,000 ug/L. The 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 33 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 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 21454, Multiple Pollutants	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6774

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 State 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; methyl tert butyl ether (MTBE), 13 ug/L (primary MCL) and 5 ug/L (secondary MCL); 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)

Title 22. Division 4. Chapter 15. Sections 64400 et seq. California Code of Regulations

Drinking Water Notification and Response Levels: An Overview

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 33 organic compounds.

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	21896	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the California Maximum Contaminant Level (MCL). One annual average datapoint exceeds the site-specific 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 14 samples exceeded the MCL. One of 5 annual average datapoints exceeded the site-specific objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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 21896, Boron	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6745

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 under the Region 6 SWAMP program. Boron concentrations in 14 quarterly samples ranged from 44 to 303 ug/L. Annual averages ranged from 54 to 261 mg/L. The annual average objective was exceeded in one of 5 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 boron concentration of 0. 2 mg/L (or 200 ug/L) and a 90th percentile level of 0.3 mg/L (or 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 below [Mojave] Forks Reservoir was sampled.

Temporal Representation:

Fourteen quarterly samples 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 major source of boron in this watershed is probably natural geothermal activity. 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 21896, Boron	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

8299

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 under the Region 6 SWAMP program. Boron concentrations in 14 quarterly samples ranged from 44 to 303 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 for boron is 1000 ug/L.

Objective/Criterion Reference:

Compilation of Water Quality Goals

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

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

Temporal Representation:

Fourteen quarterly samples 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 riverThe 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 major source of boron in this watershed is probably natural geothermal activity. 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	21645	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 samples exceeded the MCL. None of five annual average values 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 21645, Chloride	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6762

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:

The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2001 and 2005. Chloride concentrations in 15 quarterly samples ranged from 6.87 to 30.6 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 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 below [Mojave] Forks Reservoir, 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 21645, Chloride	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6746

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:

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 chloride concentration of 55 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 below [Mojave] Forks Reservoir, 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	21554	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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. 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 diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region. 3. None of six 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 21554, Dissolved oxygen saturation	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6748

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 under the Region 6 SWAMP program between 2003 and 2005. Percent saturation of dissolved oxygen in 6 measurements ranged from 105 to 133 percent. The objective was not violated..

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

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 Mojave River below [Mojave] Forks Reservoir was sampled.

Temporal Representation:

Six measurements of percent saturation were taken 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	21646	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

Pollutant:	Nitrate as Nitrate (NO3)
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 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 samples exceeded MCL or 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 21646, Nitrate as Nitrate (NO3)	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6831

Pollutant:

Nitrate as Nitrate (NO3)

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 2001 and 2005. Samples were collected and analyzed for nitrite and nitrate plus nitrite, both expressed "as N." Nitrate was calculated by subtraction using these data. The maximum value in 15 quarterly samples was 0.065 mg/L "as N" or 0.289 mg/L "as nitrate." The objective was not exceeded.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan does not include a site-specific objective for nitrogen at the "Mojave River at Forks" station (Basin Plan Table 3-21). The objective for station 2 in Table 3-20 applies upstream under the Tributary Rule. It is a maximum "nitrate as nitrate" value of 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 below [Mojave] Forks Reservoir, 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 21646, Nitrate as Nitrate (NO3)	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6832

Pollutant:

Nitrate as Nitrate (NO3)

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 under the Region 6 SWAMP program between 2001 and 2005. Samples were collected and analyzed for nitrite and nitrate plus nitrite, both expressed "as N." Nitrate was calculated by subtraction using these data. The maximum value in 15 quarterly samples was 0.062 mg/L "as N" or 0.289 mg/L "as nitrate." 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 below [Mojave] Forks Reservoir, 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	21968	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the California Maximum Contaminant Level (MCL). No biological data are available for assessment of compliance with the water quality objective for biostimulatory substances. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 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 MCL 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 water quality objective for biostimulatory substance. 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 21968, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6835

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 under the Region 6 SWAMP program between 2001 and 2005. Concentrations of nitrate plus nitrite in 5 of 15 quarterly samples were below the detection level. The remaining samples ranged from 0.008 to 0.505 mg/L. No data were available on algae or macrophytes for evaluation 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 a site-specific objective for nitrate plus nitrite. The narrative water quality 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 below [Mojave] Forks Reservoir, 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 21968, Nitrate/Nitrite (Nitrite + Nitrate as N)	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

8302

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:

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 below [Mojave] Forks Reservoir, 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	21891	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 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 California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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 21891, Nitrite	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6833

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 under the Region 6 SWAMP program between 2001 and 2005. Six of 15 quarterly samples for NO2-N were below the detection level. Nitrite concentrations in the remaining samples ranged from 0.001 to 0.009 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 nitrate is 1 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 below [Mojave] Forks Reservoir, 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	21553	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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. 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 diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region. 3. None 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 21553, Oxygen, Dissolved	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6747

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 under the Region 6 SWAMP program between 2001 and 2005. The range of dissolved oxygen concentrations in 14 quarterly samples was 6.3 to 11.9 mg/L. The objective was not violated.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

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

Objective/Criterion Reference:

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

2007. SWAMP Data for the Mojave River Watershed

Evaluation Guideline:

Guideline Reference:

Spatial Representation:

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

Temporal Representation:

Fourteen 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	21317	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 objectives for phosphorus in the Mojave River, and the narrative objective for biostimulatory substances applies. There are no data on algae or macrophytes available to determine whether excess productivity due to phosphorus occurred. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. No biological data are available for assessment whether the 6 chemical samples exceeded 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 21317, Phosphate	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6813

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 PO4-P in six quarterly samples ranged from 0.03 to 0.058 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 below [Mojave] Forks Reservoir, 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	21892	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 are no biological data for assessment whether any of the chemical 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 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. There are no biological data for use in 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 21892, Phosphorus	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6812

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 0.04 to 0.19 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:

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:

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	21973	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 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 3.2 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 21973, Specific Conductance	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6750

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 under the Region 6 SWAMP program between 2001 and 2005. Fifteen quarterly field measurements of specific conductance ranged from 190 to 615 uS/cm. Specific conductance levels in an additional two laboratory measurements taken in 2003 were 246 and 328 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 below [Mojave] Forks Reservoir was sampled.

Temporal Representation:

Fifteen quarterly field measurements of specific conductance were taken between 2001 and 2005. Two laboratory measurements were taken in March and June 2003.

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	21970	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

Pollutant:	Sulfates
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 California Maximum Contaminant Level (MCL). Three of 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 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 MCL. Three of five annual average datapoints exceeded the site-specific objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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 21970, Sulfates	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6749

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:

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 below [Mojave] Forks Reservoir was sampled.

Temporal Representation:

Fifteen quarterly samples 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):

Line of Evidence (LOE) for Decision ID 21970, Sulfates	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6751

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 under the Region 6 SWAMP program between 2001 and 3005. Sulfate concentrations in 15 quarterly samples ranged from 2.2 to 130 mg/L. Annual averages, based on 2 to 4 samples per year, ranged from 14.4 to 94.6 mg/L. The site-specific objective was exceeded in three 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 includeds an annual average sulfate concentration of 35 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 below [Mojave] Forks Reservoir was sampled.

Temporal Representation:

Fifteen quarterly samples 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	21761	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 21761, Temperature, water	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6764

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 under the Region 6 SWAMP program between 2001 and 2005. Fifteen quarterly measurements of water temperature 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 relevant language from the Lahontan Basin Plan's narrative water quality objective is: "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 below [Mojave] Forks Reservoir was sampled.

Temporal Representation:

Fifteen quarterly temperature measurements (two to four per year) 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	28379	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

Pollutant:	Total Dissolved Solids
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: 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 15 samples exceeds the California Maximum Contaminant Level (MCL). Five of the samples exceed the site-specific water quality objective, which is expressed as a maximum value. However, listing is not recommended because the samples are not temporally representative. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used 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 variation expected in streamflow and constituent concentrations in streams of the Lahontan Region. 3. None of 15 samples exceeded the MCL and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. Five of 15 samples exceeded 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. State Water Board Review and Conclusions: 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. At the June 15, 2010 State Water Board meeting for approval of the 2010 Integrated Report, the State Water Board directed staff to reevaluate the listing recommendation for this water body-pollutant combination. Based on this reevaluation, State Water Board staff recommended the listing recommendation be revised to not place this water body-pollutant combination on the 303(d) list based on the minimum numbers of samples showing exceedence of the water quality objective. On August 4, 2010 the State Water Board approved the staff recommendation to not place this water body-pollutant combination on the 303(d) list. The final language for the recommendation is the same as written under the "Regional Board Conclusion" above.

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 28379, Total Dissolved Solids	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6753

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 under the Region 6 SWAMP program between 2001 and 2005. TDS concentrations in 15 SWAMP samples ranged from 171 to 386 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 below [Mojave] Forks Reservoir 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 28379, Total Dissolved Solids	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6752

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 under the Region 6 SWAMP program between 2001 and 2005. TDS concentrations in 15 SWAMP samples ranged from 171 to 386 mg/L. Five samples exceeded the 312 mg/L maximum.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's Table 3-21 does not contain a site-specific objective for Total Dissolved Solids (TDS) at the Mojave River below Forks station. However, the objective for the West Fork Mojave River (at Lower Narrows) in Basin Plan Table 3-20 applies upstream through the Tributary Rule. This objective is a maximum of 312 mg/L TDS.

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 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	21894	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 are no biological data available to asses whether any of the chemical samples exceed 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 to assess whether any of the 11 chemical samples exceeded the objective. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.

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 21894, Total Kjeldahl Nitrogen (TKN)	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6834

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 under the Region 6 SWAMP program between 2002 and 2005. Concentrations of TKN in 11 quarterly samples ranged from 0.19 to 0.51 mg/L. No data were available on algae or macrophytes for evaluation 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 a site-specific objective for Total Kjeldahl Nitrogen (TKN). The narrative water quality 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 below [Mojave] Forks Reservoir, 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	21818	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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 21818, pH	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6899

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. In 15 quarterly field measurements, pH ranged from 7.5 to 8.9 units. Two of 15 pH values were higher than 8.5 units. Two laboratory measurements were taken in 2003; one of the pH values was an estimate and the other was 8 units.

Data Reference:

2007. SWAMP Data for the Mojave River Watershed

SWAMP Data:

SWAMP

Water Quality Objective/Criterion:

The Lahontan Basin Plan's regionwide objective for pH is as follows: "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:

2007. SWAMP Data for the Mojave River Watershed

Spatial Representation:

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

Temporal Representation:

Fifteen quarterly field measurements of pH (2 to 4 per year) were taken between 2001 and 2005. Two laboratory measurements were taken in March and June 2003.

Environmental Conditions:

QAPP Information:

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

QAPP Information Reference(s):


DECISION ID	28884	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper 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. Four of the annual average datapoints exceed the site-specific water quality objective. Nine 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. Four of five annual average datapoints exceed the site-specific objective. Nine of 14 samples exceed the California Maximum Contaminant Level 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 28884, Fluoride	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6766

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 under the Region 6 SWAMP program between 2001 and 2005. Fluoride concentrations in 14 quarterly samples ranged from 0.2 to 5.5 mg/L. Nine of 14 samples exceeded the MCL.

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 below [Mojave] Forks Reservoir, 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 28884, Fluoride	Region 6
Mojave River (Mojave Forks Reservoir outlet to Upper Narrows)

LOE ID:

6767

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:

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 (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 below [Mojave] Forks Reservoir, 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):