Browsing by Author "Coffin, Chris"
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Item Lower Yakima River Suspended Sediment Total Maximum Daily Load Study(Washington State Dept. of Ecology, 2006-05) Coffin, Chris; Plotnikoff, Robert W.; Anderson, RyanThe Washington State Department of Ecology is required, under Section 303(d) of the federal Clean Water Act and U.S. Environmental Protection Agency regulations, to develop and implement Total Maximum Daily Loads (TMDLs) for impaired waters, and to evaluate the effectiveness of these water clean-up plans to achieve the needed improvement in water quality. The Lower Yakima River Suspended Sediment and DDT TMDL was developed to reduce suspended sediment, turbidity, and the pesticide, DDT, in the lower reaches of the Yakima River. TMDL implementation is scheduled over 20 years with interim targets set at five-year intervals. The fifth-year (2003) targets included meeting Washington State water quality criterion for turbidity in the lower Yakima River during the irrigation season. Also included was the requirement that non-Yakama Reservation tributaries to the lower mainstem – especially the major tributaries of Moxee Drain, Granger Drain, Sulphur Creek, and Spring Creek – achieve a maximum 90th percentile turbidity of 25 NTU at their mouths during the irrigation season. This report presents an assessment of the turbidity within the project area and the effectiveness of the TMDL in reducing agriculturally related sediment.