The Environmental Protection Agency began testing about 600 community water well systems for pesticides in July. The testing is part of a 2-year survey of private and community wells throughout the United States designed to identify the extent of pesticide residues in drinking water wells nationwide. Testing on more than 750 private wells began in April.
EPA began the study by examining pesticide use and vulnerability of acquifers for every county in the U.S. including Alaska and Hawaii. Armed with a map of average scores of vulnerability of counties, the study's organizers selected a representative group of counties but weighted the selection toward areas of higher vulnerability and pesticide use. Once the counties were selected, vulnerability within counties was ranked and individual wells were selected. Scientists will be analyzing the water samples from the wells for more than 100 commonly used pesticides in addition to a number of pesticide metabolites, nitrites, and nitrates.