“EPA has worked closely with the USGS NAWQA Program since it began in 1991, with the goal of advancing the scientific tools and data that are available to assess the potential risks posed by pesticides in surface water and ground water. Recently, EPA and USGS have collaborated in developing statistical models to predict concentrations of atrazine and other pesticides in streams around the country, including quantitative estimates of reliability. The models, developed by USGS from NAWQA data, increase EPA’s capacity to estimate surface-water concentrations of pesticides. Model results are being used to identify locations where additional monitoring may be needed to evaluate the ecological condition of watersheds.” (Elizabeth Behl, Chief of Environmental Risk Branch, Office of Pesticide Programs, U.S. Environmental Protection Agency)

USGS Circular 1291, The Quality of Our Nation's Waters Pesticides in the Nation's Streams and Ground Water, 1992-2001