Ten pesticides and pesticide metabolites were detected in ground-water samples collected from each of 32 community water-supply (CWS) systems in central and west ern New York in August 1999. The sampling sites consisted of 30 wells that ranged from 23 to 120 feet in depth, and 2 springwater infiltration galleries. All wells tapped unconfined sand and gravel aquifers except one, wh ich was completed in karstic limestone. These systems were selected because they were deemed vulnerable to pesticide contamination; accordingly, the results are not considered representative of all CWS systems in New York. The samples were analyzed for 60 pesticides. Twenty-four of the 32 samples contained at least one pesticide, and one sample contained eight pesticides or pesticide metabolites. New York State and Federal water-quality standards were not exceeded in any sample collected in this study. All pesticides detected in the CWS wells are a specific class of herbicides that are used to control broadleaf weeds and undesirable grasses in agricultural fields, lawns, and other areas that require control of vegetation. The four compounds detected most frequently were the herbicides atrazine and metolachlor and their metabolites--deethylatrazine and metolachlor ESA. Maximum concentrations of the four compounds ranged from 0.088 micrograms per liter (?g/L) for deethylatrazine to 3.58 ?g/L for metolachlor ESA.
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USGS Numbered Series
Pesticides and their metabolites in community water-supply wells of central and western New York, August 1999