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National Water-Quality Assessment Program (NAWQA)
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Pesticide registration


Key findings from the first decade of NAWQA studies

  • Low concentrations of pesticides are in streams and ground water throughout the nation. At least one pesticide was detected in more than 95 percent of stream samples collected at 115 sites.
  • Concentrations of individual pesticides in samples were almost always below current U.S. Environmental Protection Agency (USEPA) drinking-water standards.
  • Nearly two-thirds of all streams sampled had at least one pesticide at a concentration exceeding a guideline for the protection of aquatic life.

What do these findings mean?
These findings do not necessarily translate into effects on human or aquatic health. USGS can detect these chemicals in very small amounts that are 10 to 100 times below the threshold used for setting standards and guidelines. These low-level detections allow scientists to identify and evaluate emerging issues and to track contaminant levels over time.

It is difficult to assess the potential risk to humans and to aquatic life from these chemicals. No standards or guidelines exist for many pesticides and their breakdown products. Guidelines to protect aquatic life have been developed for only 18 of the 88 pesticides NAWQA analyzes for; drinking-water standards or health advisory levels have been developed for only 52. In addition, these criteria have been developed for individual chemicals and do not account for exposure to chemical mixtures or to the high concentrations that occur in seasonal "pulses." And the potential effects on reproductive, nervous, and immune systems, as well as on chemically sensitive individuals, are not well understood.

How USEPA and the States use NAWQA pesticide data
USEPA Office of Pesticides uses USGS data for pesticide registration and for assessments of pesticide exposure. One of the performance goals of the Office of Pesticides states:

By 2010, detections of the 15 pesticides most frequently found in surface water in USGS 1994 NAWQA data will be reduced by 50 percent. Any new pesticides registered since 1996 found in USGS 2010 data for surface water will have a detection frequency no greater than 30 percent. By 2010, 50 percent of all pesticides with the potential to leach to ground water will be managed through labeling or other methods to prevent ground-water contamination.

USGS also provides USEPA with

  • ancillary data, such as on geology, hydrology, and land use, needed to interpret the monitoring data
  • computer models that predict pesticide concentrations at drinking-water intakes
  • monitoring of treated and untreated water in selected reservoirs
  • designs for a national monitoring program for pesticides in drinking water
  • data and models to support the implementation of the Food Quality Protection Act.
    NAWQA's ability to detect a wide array of contaminants by use of low laboratory detection limits allows state managers to better understand and manage pesticides.

Pesticides in Ground Water--Summary Statistics; Results of the National Water Quality Assessment Program (NAWQA), 1992-1998 and Pesticides in Streams--Summary Statistics; Results of the National Water Quality Assessment Program (NAWQA), 1992-1998



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