Pesticides in Water-Supply Reservoirs and Finished Drinking Water: A Pilot Monitoring Program

WRD PROJECT #: MD136
PROJECT CHIEF: Blomquist, Joel D.
BEGIN DATE: 01-March-1999
END DATE: 30-September-2001

Customers currently supporting the project:

U.S. Environmental Protection Agency
U.S. Geological Survey

Click here for more information on the NAWQA program in the MD-DE-DC Water Science Center

Problem

The Food Quality Protection Act (FQPA) of 1996 requires USEPA to assess aggregate risk from exposure to pesticides in drinking water. USEPA-Office od Pesticede Programs(OPP) is presently using National Water-Quality Assessment (NAWQA) program data on the occurrence of pesticides in streams and ground water for drinking water and aquatic exposure assessments, however, these data are not targeted to public water supplies. Although collecting data on the occurrence of pesticides in drinking water is not specifically within the objectives and current design of the NAWQA program, the NAWQA study teams have the infrastructure for collecting data on raw and treated drinking water to meet the data requirements of OPP. USEPA is initiating this pilot project with NAWQA to link pesticide occurrences in treatment facility intake water to drinking water and to identify watershed characteristics contributing to pesticide contamination. This study is targeted to smaller drinking-water supply reservoirs in areas with high Pesticide use. This project will provide information that can be linked to the NAWQA database on pesticide occurrences in surface water. The initial results of this program will be used to guide the design of additional National drinking-water monitoring programs for pesticide residues.

Objectives

USEPA initiated a pilot project to link the occurrence of pesticides in drinking water with data on raw-water sources and to identify watershed characteristics contributing to pesticide contamination. This project was designed to meet the multiple information requirements of USEPA-OPP, USEPA-Office of Ground-Water Drinking Water, as well as the USGS. This pilot program is principally a data-collection effort; however, the program results will be used to guide additional studies and for many other purposes including:

1. Providing monitoring data on pesticide concentrations in raw and finished drinking water.
2. Providing monitoring data on pesticide concentrations in reservoirs for ecological risk assessments.
3. Evaluating the impact of sampling frequency for measuring peak concentrations of pesticides and their degredates in public water systems.
4. Linking the occurrence of pesticides in treated drinking water with raw water and treatment processes.
5. Associating pesticide concentrations in reservoirs with watershed and reservoir characteristics.
6. Providing data for model evaluation and development.

Approach

Water utilities that rely on reservoirs were selected for this pilot monitoring program because they are considered to be highly vulnerable to pesticide contamination, serve as integrators of pesticide loading from their watersheds, and are important sources of drinking water. This pilot study is targeted to smaller drinking-water supply reservoirs in areas with high pesticide use.

Beginning in March 1999, water samples were collected from 12 reservoirs across the Nation. These reservoirs were chosen to represent a cross section of pesticide-use areas that are typical of regional cropping patterns as well as urban areas. At each reservoir, samples will be collected from three points: the finished water, raw water from the intake stream, and the reservoir outflow. Pesticide analysis will be performed using the same broad-spectrum multi-residue method employed by the NAWQA program. Two new broad-spectrum methods will also be used including an HPLC-MS method and a GCMS method. Sample collection has continued for an additional year and will extend through December 2000 at 9 of the 12 reservoirs.

Water samples will be collected by trained USGS field staff and coordinated by a USGS team leader. Coordination and reporting activities will be conducted through the USGS Maryland-Delaware-D.C. District Office. Data collection at each site will be implemented within existing NAWQA study units or USGS District offices. Standard NAWQA sample-collection protocols will be adapted for this project. In April 2000, USEPA extended the pilot program at a reduced level. Sample collection will continue for an additional year and will extend through December 2000 at 9 of the 12 reservoirs.