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Linkages between water quality and chemical use

The chemicals that are found in streams and ground water are closely linked to the chemicals used in each watershed. Sometimes, these connections show up quickly.

For example, a 1992-96 NAWQA study in the White River Basin, Indiana, showed that concentrations of acetochlor increased and alachlor concentrations decreased in streams within 1-2 years after acetochlor partially replaced alachlor as an herbicide used on corn.

Reducing the amount of chemicals used and applying these chemicals more efficiently can help reduce contaminant levels in both urban and agricultural areas. Currently, however, we don't have enough information on chemical use, particularly in urban areas. Improved tracking of chemical use is needed to support water-resource management actions.

Localities and states recognize the need for tracking chemical use

In King County, Washington, a USGS study found 23 of 98 pesticides in streams in 10 urban and suburban watersheds. Homeowner use was indicated as the source of some insecticides, such as diazinon, and some herbicides, such as 2,4-D, which are commonly sold in home and garden stores.

To encourage homeowners to use fewer pesticides, the county uses Fact Sheet 067-97 Pesticides in Selected Small Streams in the Puget Sound Basin, 1987-1995. Almost half of the pesticides found in the streams had no retail sales within Seattle or the surrounding area, indicating that these pesticides came from commercial applications, such as along road rights-of-way. This information helps local officials to manage chemical use.

USGS detected many pesticides in agricultural and urban streams in the Willamette Basin, Oregon. Many of the compounds occurred at elevated concentrations, often exceeding guidelines to protect aquatic life. Lack of information on pesticide use, however, made it difficult to assess the source of the pesticides and how they were transported to the water.

Concerned Oregon citizens and stakeholders used these findings to support a law that requires pesticide use to be reported. The Oregon House and Senate passed the bill by wide margins, and it was supported by both environmentalists and pesticide users.

Three states--Oregon, California, and New York-now require pesticide-use tracking. Oregon's law is unique in its provision for reporting pesticide use in urban areas, including home and garden use.

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