EAST SAN JOAQUIN WATER QUALITY FRAMEWORK: THE APPROACH

摘要

The East San Joaquin Water Quality Framework, funded by California Proposition 13 DrinkingrnWater Program funds, was created to provide a watershed organizational structure forrncooperative and coordinated water quality improvement activities. The Framework study arearnencompasses approximately 600,000 acres in the California San Joaquin Valley, including areasrnserved by five irrigation districts: Oakdale, South San Joaquin, Modesto, Turlock, and Merced.rnWork conducted under the Framework includes water quality monitoring, best managementrnpractices and implementation activities, and education and outreach to the urban and agriculturalrncommunities. In order to focus the 2006 monitoring program, a comprehensive analysis wasrnundertaken using 2000-2005 water quality monitoring data collected by state, federal and localrnagencies, cities and counties, National Pollutant Discharge Elimination System (NPDES)rnpermittees, irrigation districts, water quality coalitions, universities and other entities. Thernanalysis includes spatially explicit pesticide use data, land use information, and detailedrnwatershed mapping. The historical data analysis and the 2006 data provide insight into the naturernof the water quality issues and assists in developing specific recommendations for managementrnpractices and implementation strategies in the Framework area. Water quality constituents thatrnare consistently elevated in the area include organophosphate pesticides such as diazinon andrnchlorpyrifos, herbicides such as diuron, and inorganics such as copper, lead and zinc. In addition,rnseveral other pesticides have been detected in surface waters at levels exceeding screeningrnthresholds, including carbaryl, malathion, simazine, diuron, oryzalin, and azinphos-methyl.