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Groundwater Survey Summary

NATIONAL PESTICIDE SURVEY

Project Update
Winter 1991

NPS Phase I Report Available from NTIS

Results of the U.S. Environmental Protection Agency's National Survey of Pesticides in Drinking Water Wells (the National Pesticide Survey or NPS) are now available. You can order copies of the Survey's 500-page Phase I Report from the National Technical Information Service (NTIS), at a cost of $35.00 per copy plus $3.00 for handling. Request The National Pesticide Survey: Phase I Report, PB91-125765, by writing NTIS at the following address and enclose a check or money order:

National Technical Information Service
5285 Port Royal Road
Springfield, Virginia 22161
(703) 487-4650

Summary of Phase I Activities and Results

The National Pesticide Survey was undertaken to evaluate the presence of pesticides, pesticide degradates, and nitrate in drinking water wells in the United States. The Survey lasted over five years and cost more than $12 million. It collected extensive data, including both samples of well water and detailed questionnaire responses, about community water system wells and rural domestic wells throughout the country. Well water samples were analyzed for the presence of 127 analytes, including 101 pesticides, 25 pesticide degradates, and nitrate. Detections of the analytes were reported when the concentration round was greater than the Survey's specified minimum reporting limits.

The Phase I results of the Survey indicate that about 52.1% of the 94,600 community water system wells in the United States contain nitrate, about 10.4% contain one or more pesticides, and about 7.1% contain both. Of the approximately 10.5 million rural domestic wells, EPA estimates that about 57.0% contain nitrate, about 4.2% contain one or more pesticides, and about 3.2% contain both. EPA estimates that at most 0.8% of community water system wells (750 wells) contain one or more pesticides at levels above health-based limits and approximately 0.6% of rural domestic wells (60,900 wells) contain one or more pesticides above health-based limits.EPA also estimates that approximately 1.2% of community water system wells (1,130 wells)exceed the health-based limit for nitrate and that approximately 2.4% of rural domestic wells (254,000 wells) exceed the health-based limit for nitrate.

The NPS Phase I Report provides a detailed summary of the Survey results and the procedures that were followed to obtain them. It describes the Survey's background, design and implementation, analyte selection and analytic methods, and quality assurance/quality control procedures. Detailed descriptions of the statistical methodology and Survey procedures are also included, plus copies of all of the questionnaires used to gather data. Finally, the Phase I Report provides an extensive summary of the Survey findings and results, based upon the data obtained from the analysis of well water samples and the data obtained from Survey questionnaires.

Phase II is Underway

EPA currently is conducting a number of statistical analyses using the data compiled from chemical analyses of water samples, NPS questionnaires, and other sources to investigate the potential causes and consequences of pesticide residues and nitrate in drinking water wells. EPA will investigate the association of pesticides and nitrate in drinking water wells with such factors as pesticide and fertilizer use, ground-water vulnerability characteristics, and well characteristics. The results of this Phase II analysis will be provided in the National Pesticide Survey Phase II Report later in 1991.

NPS Fact Sheets

EPA has prepared a number of fact sheets on selected topics concerning the National Pesticide Survey. These free fact sheets are available by writing to EPA's Drinking Water Resource Center (WH 550, 401 M Street SW, Washington, D.C. 20460). The fact sheets address the following topics:

Project Summary             Summary of Results       Survey Design
Analytical Methods          Survey Analytes          Glossary
Quality Assurance/          How EPA Will Use         Fact Sheet for each
Quality Control             The NPS Results          detected analyte