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CaliforniWegional Water Quality Cc rol Board F <br /> Central Valley Region <br /> Katherine Hart, Chair ° <br /> 11020 Sun Center Drive.#200,Rancho Cordova,California 95670-6114 <br /> Matthers Rodriquez (916)464-3291 • FAX(916)464-4645 Edmund G.Brown Jr. <br /> Secreiary for http://www.waterboards.ca.gov/centralvalley Governor <br /> Environmental Protection <br /> 5January 2012 RECEIVED <br /> Ms. Judith Raybourn J/AN 0 6 2012 <br /> 30999 Koster Road <br /> Tracy, CA 95304-8825 ENVp RNMEN RL ICES <br /> DRINKING WATER QUALITY RESULTS, DOMESTIC WELL AT 30999 KOSTER ROAD, <br /> SAN JOAQUIN COUNTY <br /> Thank you for permitting California Regional Water Quality Control Board, Central Valley <br /> Region (Central Valley Water Board) staff to sample the domestic water supply well at <br /> 30999 Koster Road in Tracy. The well was sampled from a hose bib at the pressure tank on <br /> 14 September 2011. The analytical results are attached, and are summarized below. <br /> Two samples were analyzed for carbofuran, diuron and other carbamate-urea and chlorinated <br /> herbicides, some of which had been detected in groundwater in the past at Trinkle & Boys <br /> Flying Service, a pesticide applicator that operated nearby at 31244 South Highway 33. <br /> Central Valley Water Board also sampled your well for nitrate, metals, and volatile organic <br /> compounds. <br /> Your water did not contain any compounds that were associated with Trinkle & Boys Flying <br /> Service, and did not contain any volatile organic organic compounds. Your water did, <br /> however, contain small amounts of barium, cadmium, chromium, copper, vanadium, and <br /> nitrate. You can see from Table 1 that the concentrations detected in your water are below <br /> drinking water standards, which are called Maximum Contaminant Levels (MCLs). <br /> Table 1. Water Quality Results of 30999 Koster Road, 14 September 2011 <br /> Compound Sample 1 Sample 2 Maximum Contaminant <br /> Level <br /> Carbofuran <0.09 ug/L <0.09 ug/L 18 ug/L <br /> Diuron <0.09 ug/L <0.09 ug/L 2 ug/L' <br /> Nitrate as N 7.10 mg/L 7.16 mg/L 10 mg/L <br /> Arsenic (dissolved) <10.0 ug/L 1.7 J ug/L 10 ug/L <br /> Barium (dissolved) 25.6 ug/L 25.1 ug/L 1,000 ug/L <br /> Cadmium (dissolved) <10.0 ug/L 0.4 J ug/L 5 ug/L <br /> Chromium (dissolved) 24.6 ug/L 23.9 ug/L 50 ug/L <br /> Copper (dissolved) <20.0 ug/L 3.4 J ug/L 1,000 ug/L <br /> Vanadium (dissolved) 3.6 J ug/L <20.0 ug/L 63 ug/L2 <br /> Zinc (dissolved) <20 ug/L <20 ug/L 5,000 ug/L <br /> ' No Maximum Contaminant Level available. USEPA Health Advisory one-in-a-million incremental cancer risk <br /> estimate for drinking water referenced. <br /> 2 No Maximum Contaminant Level available. USEPA IRIS Reference Dose as a drinking water level referenced. <br /> California Environmental Protection Agency <br /> cl*Recycled Paper <br />