Final California 2020 Integrated Report (303(d) List/305(b) Report)

Supporting Information

Regional Board 5 - Central Valley Region

Water Body Name: Tiger Creek (below Tiger Creek Regulator Reservoir to Mokelumne River, N Fork)
Water Body ID: CAR5326006320041214082401
Water Body Type: River & Stream
 
DECISION ID
90672
Region 5     
Tiger Creek (below Tiger Creek Regulator Reservoir to Mokelumne River, N Fork)
 
Pollutant: Indicator Bacteria
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)(2016)
Revision Status Original
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA 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. Zero of three water samples exceed the evaluation guidelines for either fecal coliform or total coliform.

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 CWA section 303(d) List.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. Zero of three water samples exceed the evaluation guidelines for either fecal coliform or total coliform, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 26 samples is needed to determine if a beneficial use is fully supported using 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 Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 90672, Indicator Bacteria
Region 5     
Tiger Creek (below Tiger Creek Regulator Reservoir to Mokelumne River, N Fork)
 
LOE ID: 59240
 
Pollutant: Fecal Coliform
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: None
 
Beneficial Use: Water Contact Recreation
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: Not Specified
Data Used to Assess Water Quality: Zero of the three samples exceeded the fecal coliform objective.
Data Reference: Data for Various Projects by Pacific Gas and Electric Company, 2002-2010.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: In waters designated for contact recreation (REC-1), the fecal coliform concentration shall not exceed 400/100ml. Basin Plan for the Sacramento River and San Joaquin River Basins.
Objective/Criterion Reference: Water Quality Control Plan for the California Regional Water Quality Control Board Central Valley Region, Sacramento and San Joaquin River Basins. 4th ed
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: The samples were collected at site TC1, Tiger Creek below Tiger Creek Regulator Dam.
Temporal Representation: The samples were collected once every three months from March to September 2008.
Environmental Conditions:
QAPP Information: The data was collected under the Mokelumne River Project 2008 Water Quality Monitoring Program Report.
QAPP Information Reference(s): Quality Assurance Program Plan for Projects Requiring Water Quality and/or Water Temperature Monitoring, Version 4.
 
 
DECISION ID
87918
Region 5     
Tiger Creek (below Tiger Creek Regulator Reservoir to Mokelumne River, N Fork)
 
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)(2016)
Revision Status Original
Impairment from Pollutant or Pollution: Pollutant
 
Regional Board Conclusion: This pollutant is being considered for placement on the CWA 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. The three available water sample results were do not exceed the water quality objective for Nitrate (as N), the MCL of 10 mg/L, for the MUN beneficial use.

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 CWA section 303(d) List.

This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. The single sample result does not exceed the evaluation guideline for COMM, and this sample size is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating. A minimum of 16 samples is needed to determine if a beneficial use is fully supported using table 3.1.
4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
 
Regional Board Decision Recommendation: After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list. The readily available data and information is insufficient to determine, with the power and confidence of the Listing Policy, the applicable beneficial use support rating.
 
State Board Review of Regional Board Conclusion and Recommendation:
 
State Board Decision Recommendation: After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board.
 
 
Line of Evidence (LOE) for Decision ID 87918, Nitrate
Region 5     
Tiger Creek (below Tiger Creek Regulator Reservoir to Mokelumne River, N Fork)
 
LOE ID: 59483
 
Pollutant: Nitrate
LOE Subgroup: Pollutant-Water
Matrix: Water
Fraction: Total
 
Beneficial Use: Municipal & Domestic Supply
 
Number of Samples: 3
Number of Exceedances: 0
 
Data and Information Type: PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: 0 of the 3 samples do not exceed the water quality objective for Nitrate (as N). The Nitrate (as N) MCL objective is 10 mg/L. 1 of the 3 was reported as a non-detect. This non-detect is less than or equal to the water quality standard, the value will be considered as meeting the water quality standard, objective, criterion, or evaluation guideline.
Data Reference: Data for Various Projects by Pacific Gas and Electric Company, 2002-2010.
 
SWAMP Data: Non-SWAMP
 
Water Quality Objective/Criterion: Water Quality Control Plan, Central Valley Sacramento and San Joaquin River Region (2007): Waters designated for MUN shall not contain concentrations of chemical constituents in excess of the MCL specified in Title 22 of the California Code of Regulations. The nitrate (as N) MCL is 10 mg/L.
Objective/Criterion Reference: Maximum Contaminant Levels for organic and inorganic chemicals. CCR Title 22
 
Evaluation Guideline:
Guideline Reference:
 
Spatial Representation: Samples were collected at TC1 (Tiger Creek below Tiger Creek Regulator Dam).
Temporal Representation: Samples were collected from March to Sept 2008.
Environmental Conditions:
QAPP Information: No quality assurance information was provided.
QAPP Information Reference(s): Quality Assurance Program Plan for Projects Requiring Water Quality and/or Water Temperature Monitoring, Version 4.