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

# Supporting Information

## Regional Board 5 - Central Valley Region

Water Body Name: | Concow Creek (tributary to West Branch Feather River, Butte County)
Water Body ID: | CAR5186003120080623173308
Water Body Type: | River & Stream

DECISION ID | 13137
Pollutant: | Unknown Toxicity
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Source Unknown
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | 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. Four of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification 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 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. Four of 10 samples tested with Ceriodaphnia exceeded the narrative toxicity objective (survival and/or reproductive toxicity) and this exceeds 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.
RWQCB Board Decision / Staff Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be placed on the section 303(d) list because applicable water quality standards are exceeded and a pollutant contributes to or causes the problem.
SWRCB Board Decision / Staff Recommendation: |
USEPA Decision: |

Lines of Evidence (LOEs) for Decision ID 13137

LOE ID: | 21889
Pollutant: | Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 10
Number of Exceedances: | 3
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | Three of the 10 samples tested with Ceriodaphnia dubia exhibited reproductive toxicity and violated the narrative toxicity objective. Reproductive toxicity occurred in samples collected on the following dates (percent of control is indicated in parentheses): 15 July 2002 (78), 15 April 2003 (73), and 12 November 2003 (62).
Data Reference: | Oroville Facilities Relicensing-FERC Project No. 2100. Contaminant accumulation in fish, sediments, and the aquatic food chain. Sacramento, CA: State of CA Department of Water Resources
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. This objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances (CVRWQCB, 2007).
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Statistically significant difference from control using a t-test with 7-day chronic-style (reproduction endpoint) toxicity tests (USEPA, 1994).
Guideline Reference:
Spatial Representation: | Samples were collected from Concow Creek at Jordan Hill Road.
Temporal Representation: | Samples were collected on the following dates: 15 May 2002, 15 July 2002, 24 September 2002, 12 November 2002, 18 February 2003, 15 April 2003, 15 July 2003, 16 September 2003, 12 November 2003, and 18 February 2004. Sampling events were conducted during the high temperature months of July and September, following the first flush in the fall, following winter dormant spraying in February, and again during the high runoff period in April or May.
Environmental Conditions: |
QAPP Information: | DWR. 2005. Quality Assurance Project Plan for Oroville Facilities Relicensing
QAPP Information Reference(s):
LOE ID: | 21888
Pollutant: | Toxicity
LOE Subgroup: | Toxicity
Matrix: | Water
Fraction: | Total
Beneficial Use: | Warm Freshwater Habitat
Aquatic Life Use: | Warm Freshwater Habitat
Number of Samples: | 10
Number of Exceedances: | 1
Data and Information Type: | TOXICITY TESTING
Data Used to Assess Water Quality: | One of the 10 samples tested with Ceriodaphnia dubia was toxic (survival endpoint) and violated the narrative toxicity objective. The toxic sample was collected on 16 September 2003. This sample had 60 percent survival, which represented 60 percent of control.
Data Reference: | Oroville Facilities Relicensing-FERC Project No. 2100. Contaminant accumulation in fish, sediments, and the aquatic food chain. Sacramento, CA: State of CA Department of Water Resources
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human, plant, animal, or aquatic life. This objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances (CVRWQCB, 2007).
Objective/Criterion Reference: | Central Valley Regional Water Quality Control Board. Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board - Central Valley Region
Evaluation Guideline: | Statistically significant difference from control using a t-test with 7-day survival toxicity tests.
Guideline Reference:
Spatial Representation: | Samples were collected from Concow Creek at Jordan Hill Road.
Temporal Representation: | Samples were collected on the following dates: 15 May 2002, 15 July 2002, 24 September 2002, 12 November 2002, 18 February 2003, 15 April 2003, 15 July 2003, 16 September 2003, 12 November 2003, and 18 February 2004. Sampling events were conducted during the high temperature months of July and September, following the first flush in the fall, following winter dormant spraying in February, and again during the high runoff period in April or May.
Environmental Conditions: |
QAPP Information: | DWR. 2005. Quality Assurance Project Plan for Oroville Facilities Relicensing
QAPP Information Reference(s):