| Water Body Name: | Walker Creek |
| Water Body ID: | CAR2011201319980928173807 |
| Water Body Type: | River & Stream |
Lines of Evidence (LOEs) for Decision ID 9432 |
| LOE ID: | 8768 |
| Pollutant: | Temperature, water |
| LOE Subgroup: | Pollutant-Water |
| Matrix: | Water |
| Fraction: | None |
| Beneficial Use: | Cold Freshwater Habitat |
| Number of Samples: | 7 |
| Number of Exceedances: | 2 |
| Data and Information Type: | PHYSICAL/CHEMICAL MONITORING |
| Data Used to Assess Water Quality: | Water quality assessment was conducted at the Walker Creek Creek watershed as part of SWAMP study in Winter 2001, and Spring 2002. Continuous field monitoring at 15 minute increments of temperature, dissolved oxygen, pH and specific conductance was conducted to determine temporal variability in basic water quality at 5 locations.
The 14.8 °C criterion for coho salmon was exceeded in 2 out of 7 continuous temperature deployments during the dry summer season at the downstream reach of the creek. The 17 °C criterion for steelhead was never exceeded. |
| Data Reference: | Water Quality Monitoring and Bioassessment in Nine San Francisco Bay Region Watersheds: Walker Creek, Lagunitas Creek, San Leandro Creek, Wildcat Creek/San Pablo Creek, Suisun Creek, Arroyo Las Positas, Pescadero Creek/Butano Creek, San Gregorio Creek, and Stevens Creek/Permanente Creek. Oakland, CA: Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board |
| Data collected by the Surface Water Ambient Monitoring Program, San Francisco Bay Regional Water Quality Control Board. Years 4 and 5 Assessment | |
| Water Quality Objective/Criterion: | Temperature objectives for enclosed bays and estuaries are specified in the "Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays of California" including any revisions to the plan. In addition, the following temperature objectives apply to surface waters: The natural receiving water temperature of intrastate waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Water Board that such alteration in temperature does not adversely affect beneficial uses.
The temperature of any cold or warm freshwater habitat shall not be increased by more than 5°F (2.8°C) above natural receiving water temperature. |
| Objective/Criterion Reference: | San Francisco Bay Basin (Region 2) Water Quality Control Plan (Basin Plan) |
| Evaluation Guideline: | Sullivan et al. (2000) reviewed a wide range of studies incorporating information from laboratory-based research, field observations, and risk assessment approaches and developed criteria for assessing temperature risk to aquatic life. The 7-day mean temperature (maximum value of the 7-day moving average of the daily mean temperature) of 14.8°C was established as the upper threshold criterion for coho salmon and 17.0°C for steelhead trout. The risk assessment approach used by Sullivan et al. (2000) suggests that temperatures exceeding the above thresholds will cause 10% reduction in average growth compared to optimal conditions. |
| Guideline Reference: | An Analysis of the Effects of Temperature on Salmonids of the Pacific Northwest with Implications for Selecting Temperature Criteria |
| Spatial Representation: | There were 5 locations on Walker Creek ranging from lower to upper watershed regions. |
| Temporal Representation: | Continuous deployments with 15 minute increment sampling in Winter 2001 and Spring 2002. |
| Environmental Conditions: | The Walker Creek watershed has a drainage area of 73 square miles, mostly in northwestern Marin County, with a small portion in Sonoma County. Significant tributaries to Walker Creek include Keys Creek (also known as Keyes), which flows through the gentle hills east of Tomales,
joining Walker Creek near Tomales Bay; Chileno Creek, which flows through Chileno Valley; and, in the upper watershed, Salmon Creek and Arroyo Sausal Creek, which flow through Hicks Valley. Frink and Verde Canyons each support ephemeral streams that join Walker Creek upstream from Chileno Creek. Soulajule Reservoir impounds the 15 square mile drainage of Arroyo Sausal. |
| QAPP Information: | All samples were collected and analyzed using procedures comparable with the SWAMP Quality Assurance Management Plan (SWRCB 2002). |
| QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version) |
Lines of Evidence (LOEs) for Decision ID 4224 |
| LOE ID: | 3714 |
| Pollutant: | Mercury |
| LOE Subgroup: | Pollutant-Tissue |
| Matrix: | Tissue |
| Fraction: | Not Recorded |
| Beneficial Use: | Commercial or recreational collection of fish, shellfish, or organisms |
| Number of Samples: | 0 |
| Number of Exceedances: | 0 |
| Data and Information Type: | Not Specified |
| Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006. |
| Data Reference: | Placeholder reference pre-2006 303(d) |
| Water Quality Objective/Criterion: | Unspecified |
| Objective/Criterion Reference: | Placeholder reference pre-2006 303(d) |
| Evaluation Guideline: | Unspecified |
| Guideline Reference: | Placeholder reference pre-2006 303(d) |
| Spatial Representation: | Unspecified |
| Temporal Representation: | Unspecified |
| Environmental Conditions: | Unspecified |
| QAPP Information: | Unspecified |
| QAPP Information Reference(s): | |