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(010) Exposure Assessment Model for Diazinon Sources in the Sacramento and Feather Rivers.
Snyder, Nathan1, Denton, Debra2, Troyan, Jerrold3, Williams, W.*,1, 1 Waterborne Environmental, Inc., Leesburg, VA, USA2 U.S. Environmental Protection Agency, Sacramento, CA, USA3 Sacramento Regional County Sanitation District, Mather, CA, USA
ABSTRACT- Environmental fate and transport models are being utilized to identify and quantify important regional sources of diazinon to the Sacramento and Feather Rivers in California, and to evaluate the feasibility of mitigation measures as necessary to help ensure concentrations are within compliance with target levels. The modeling approach involves the linkage of two simulation models: the U.S. Environmental Protection Agency's Pesticide Root Zone Model (PRZM) and the water quality model for riverine environments (RIVWQ). A geographical information system was used to integrate spatially varying data for model setup. Data sources include diazinon use records from the California Pesticide Use Reports, soil properties based on the U.S. Department of Agriculture's soil database, the drainage system from the National Hydrography data set, channel geometry from previous modeling by U.S. Army Corps of Engineers and the California Department of Water Resources, and historical weather data and streamflow data from the National Oceanic and Atmospheric Administration and the U.S. Geological Survey, respectively. Water quality monitoring conducted by Sacramento River Watershed Program and the USGS is being used for model calibration. The model is being used to evaluate alternative management strategies, such as different application rates and application timing to assist with evaluating the diazinon implementation plan for the Sacramento and Feather River's Total Daily Maximum Load.
Key words: modeling, diazinon, pesticides, TMDL
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