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

# Supporting Information

## Regional Board 5 - Central Valley Region

Water Body Name: | Cache Creek, North Fork (below Indian Valley Reservoir, Lake County)
Water Body ID: | CAR5134004020080731215753
Water Body Type: | River & Stream

DECISION ID | 12834
Pollutant: | Mercury
Final Listing Decision: | List on 303(d) list (being addressed by USEPA approved TMDL)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Sources: | Resource Extraction
TMDL Name: | Cache Creek, Bear Creek, and Harley Gulch Mercury TMDL Project
TMDL Project Code: | 127
Date TMDL Approved by USEPA: | 02/07/2007
Impairment from Pollutant or Pollution: | Pollutant
Weight of Evidence: | This pollutant is being considered for placement on the section 303(d) list under section 3.5 of the Listing Policy. Under section 3.5 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. 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. There is sufficient justification to place it in the Being Addressed portion of the 303(d) list because a TMDL has been completed and approved by the Central Valley RWQCB and USEPA, and is expected to result in attainment of the standard. 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 average concentration of mercury in fish tissue of trophic level 3 fish exceeds the site-specific water quality objective in the Basin Plan. The average concentration for trophic level 4 fish does not exceed the objective. 4. The Cache Creek, Bear Creek, and Harley Gulch TMDL for Mercury has been approved by the Central Valley RWQCB in 2005 and approved by USEPA on February 7, 2007. 5. 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 12834

LOE ID: | 22565
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Tissue
Matrix: | Tissue
Fraction: | Total
Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms
Number of Samples: |
Number of Exceedances: |
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | For purposes of evaluating placement on the 303(d) list, the water quality objectives were compared with the available data. The two lines of evidence were combined to make averaging of the concentration data possible. Existing data were collected in three non-consecutive years and had a broader size range of fish for the TL4 species than described in the Basin Plan. The water quality objectives are intended to protect humans and wildlife species such as osprey, bald eagle, and river otter that eat large fish. Therefore, all TL3 and TL4 fish with total lengths greater than 150 mm were included in this assessment. Use of a broader size range was necessary as there were not enough fish in the 250-350 range to obtain average concentrations. For trophic level 3 fish, tissue was analyzed from rainbow trout and Sacramento sucker: 24 samples, average 0.19 ppm. The trophic level 3 water quality objective was exceeded. For trophic level 4 fish, tissue was analyzed from Sacramento Pikeminnow and Smallmouth Bass: 18 samples, average 0.17 ppm. The trophic level 4 water quality objective was not exceeded.
Data Reference: | CVRWQCB. 2004. TMDL Fish Tissue Sampling- Cache Creek and Sacramento River Watersheds. Central Valley Regional Water Quality Control Board; and California Department of Fish and Game. Unpublished Data. August 2004.
| Mercury Bioaccumulation and Trophic Transfer in the Cache Creek Watershed, California, in Relation to Diverse Aqueous Mercury Exposure Conditions. CALFED Mercury Program Final Project Report. January 25, 2004
Water Quality Objective/Criterion: | Trophic Level 3 Fish: 0.12 mg methylmercury/ kg (ppm) wet weight of muscle as the average concentration in samples of one or more species of trophic level 3 fish in the length ranges of 250-350 mm or >125 mm for Green Sunfish and Bluegill. The representative fish species are Green Sunfish, Bluegill, Sacramento Sucker and Rainbow Trout. Trophic Level 4 Fish: 0.23 mg methylmercury/ kg (ppm) wet weight of muscle tissue as the average concentration in samples of one or more species of trophic level 4 fish in the length range 250-350 mm. The representative fish species are Sacramento Pikeminnow, Largemouth Bass, Smallmouth Bass and Channel Catfish. The Basin Plan requires that in order to show that a mercury control program has succeeded in removing an impairment, average concentrations in fish tissue must be equal to or less than the water quality objectives for three consecutive years.
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: |
Guideline Reference:
Spatial Representation: | Samples were collected at one location from the North Fork of Cache Creek directly downstream of the confluence with Benmore Canyon.
Temporal Representation: | Fish samples were collected during three sampling events: on 11/14/2000, 11/22/2000 and 9/30/2003.
Environmental Conditions: |
QAPP Information: | Data quality: Excellent... Quality Control for all of the elements described in section 6.1.4 of the Policy was conducted in accordance with the CALFED Mercury Project QAPP (Puckett and van Buuren, 2000).
QAPP Information Reference(s):