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| Title | Willapa River Watershed Temperature Total Maximum Daily Load Study | |||
| Month-Year Published | September 2004 | |||
| Online Availability |
3421 kilobytes, requires version 4.0 or later of Adobe Acrobat Reader Software get Acrobat Reader
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| Short Description |
This technical assessment uses effective shade as a surrogate measure of heat flux to fulfill the requirements of the federal Clean Water Act Section 303(d) for a Total Maximum Daily Load (TMDL) for temperature. Substantial reductions in water temperature are predicted for hypothetical conditions with mature riparian vegetation, improvements in riparian microclimate, and reduction of channel width. Potential reduced temperatures are less than the Class A standard of 18°C in almost all stream segments evaluated. In addition to load allocations for effective shade, activities to reduce incoming sediment and increase channel complexity are recommended for compliance with the water quality standards for water temperature. On January 5, 2005, changes were made in column 5 of Table E1 in the attached pdf. (Also see abstract below) | |||
| Publication Number | 04-03-024 | |||
| Author(s) | Stohr, A. | |||
| Print Availability | ||||
| Number of pages | 80 p. + app. (144 p. total) | |||
| Keywords | basin, creek, fish, river, study, temperature, Total Maximum Daily Load, water, watershed | |||
| Subject Waterbodies |
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| Related Publications | Title | Relationship | ||
| Quality Assurance Project Plan: Willapa River Temperature Total Maximum Daily Load | supporting publication | |||
| Flow Summary for Gaging Stations on the Willapa River and Selected Tributaries | similar topic | |||
| Abstract | Long Description |
The Willapa River basin contains high quality anadromous fish habitat that supports Fall Chinook, Coho, Fall Chum, and Winter Steelhead. The 303(d) listings for temperature in streams in the basin include the mainstem Willapa River and Fork Creek. Substantial reductions in water temperature are predicted for hypothetical conditions with mature riparian vegetation, improvements in riparian microclimate, and reduction of channel width. Potential reduced temperatures are predicted to be less than the Class A standard of 18°C in almost all segments of the streams evaluated. This technical assessment uses effective shade as a surrogate measure of heat flux to fulfill the requirements of the federal Clean Water Act Section 303(d) for a Total Maximum Daily Load (TMDL) for temperature. Effective shade is defined as the fraction of incoming solar shortwave radiation above the vegetation and topography that is blocked from reaching the surface of the stream. In addition to load allocations for effective shade, other management activities are recommended for compliance with the water quality standards for water temperature, including measures to increase channel stability and complexity. |
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