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State Water Resources Control Board <br /> Division of Water Quality <br /> GAMA Program <br /> GROUNDWATER INFORMATION SHEET <br /> Nitrate <br /> The purpose of this groundwater information sheet is to provide general information regarding <br /> a specific constituent of concern (COC). The information provided herein relates to wells <br /> (groundwater sources) used for public drinking water, not water served at the tap. <br /> GENERAL INFORMATION <br /> Constituent of Concern Nitrate <br /> Aliases None <br /> Chemical Formula Nitrate (NO3) <br /> CAS No. Nitrate 14797-55-8 <br /> Storet No. 71850 <br /> Summary Nitrate is a regulated drinking water contaminant with an <br /> established State Maximum Contaminant Level of 10 mg/L (as N) <br /> or 45 mg/L (as NOs). Nitrate is produced in the atmosphere from <br /> nitrogen and occurs naturally in groundwater at concentrations <br /> typically below 2 mg/L (as N). High concentrations of nitrate in <br /> groundwater are often associated with the use of fertilizers or <br /> animal/human wastes. Based on SWRCB data from 2007 to <br /> 2017, 854 active and standby public water supply wells (of <br /> 11,906 wells sampled) had at least one detection of nitrate (as N) <br /> above the MCL. Most wells with nitrate detections above the <br /> MCL occurred in Los Angeles (128 wells), Tulare (95 wells), and <br /> Kern (88 wells) counties. <br /> Revised November 2017 1 <br />