USGS Report - How Healthy Are Our Rivers and Streams?

America's rivers and streams are generally suitable for irrigation, drinking water, and home and recreational uses. However, in areas with significant agricultural and urban development, the quality of our nation's water resources has been degraded by contaminants such as pesticides, nutrients, and gasoline-related compounds.

The USGS has released a series of 15 reports on the health of major river basins across the country. Findings of regional and national interest are highlighted in a separate report "Water Quality in the Nation's Streams and Aquifers-Overview of Selected Findings, 1991-2001." Major challenges that continue to affect streams and ground water are sources of pesticides, nutrients, metals, gasoline-related compounds and other contaminants. In urban areas, insecticides such as diazinon and malathion which are commonly used on lawns and gardens were found in nearly all of the streams that were sampled. Streams in agricultural areas were more likely to contain herbicides-especially atrazine, metolachlor, alachlor, and cyanazine. Concentrations of contaminants in well water samples were almost always lower than current EPA drinking- water standards and guidelines. However, the possible risk to people and to aquatic life can only be partially addressed because of the lack of criteria for many chemicals and their degradation or "breakdown" products. In addition, criteria were developed for individual chemicals and do not take into account exposure to mixtures or seasonal high pulses in concentrations.

The detection of chemicals at low levels does not automatically translate into impacts on human or aquatic health. For example, USGS water quality assessments may be done at the parts-per- trillion levels, an amount that can be up to 100 times lower than the threshold used for setting standards and guidelines. The reports on water quality were completed by the USGS National Water Quality Assessment (NAWQA) program. Of the 51 areas studied in the first phase of the program, the USGS has already launched a second round of studies in 42 areas to determine trends, fill critical gaps in the characterization of water-quality conditions, and increase understanding of natural and human factors that affect water quality. Free copies of the NAWQA reports are available from 1-888-ASK-USGS, by fax 303-202-4693 or online at http://pubs.water.usgs.gov/nawqasum/.