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EPA Unveils First-Ever Assessment of U.S. Wadeable Streams

Release Date: 05/05/2006
Contact Information: Dale Kemery, (202) 564-4355 /

(Washington, D.C. - May 5, 2006) What's the state of the union's streams? EPA set out to answer that question in a just-completed, multiyear study of wadeable streams across the country.

The study, Wadeable Streams Assessment (WSA), is the first consistent evaluation of the streams that feed rivers, lakes, and coastal waters. Alaska and Hawaii were not included in the report but have pilot projects underway. "Wadeable streams" are those which are shallow enough to be adequately sampled without a boat. They are essential natural resources that have been under-sampled in the past.

"This scientific report card on America's streams will help citizens and governments measure the health of their watersheds, take actions to prevent pollution, and monitor for progress," said Assistant Administrator for Water Benjamin H. Grumbles. "Small streams are connected to the overall health of a community's ecology and economy and this report underscores their importance and identifies priority work ahead."

Conducted between 2000 and 2004, the study was based on sampling at 1,392 sites selected to represent the condition of all streams that share similar ecological characteristics in various regions. It was a collaborative effort that involved dozens of state environmental and natural resource agencies, federal agencies, universities and other organizations. More than 150 field biologists were trained to collect environmental samples using a standardized method.

What Did They Find?

The survey found that stream conditions vary widely across the diverse ecological regions of the country, and that streams in the West were in the best condition. Humans, the researchers found, have a significant impact on wadeable streams. A majority of streams showed evidence of human influence along the streams, such as dams, pavement and pastures.

The WSA measured key chemical and physical indicators that reveal stress, or degradation of streams. The most widespread stressors observed are nitrogen, phosphorus, and streambed sediments, which smother aquatic habitat and degrade conditions for fish. Nitrogen and phosphorus are nutrients that can increase the growth of algae, decrease levels of dissolved oxygen and cloud the water.

What's Next?

The WSA is part of a series of surveys to evaluate all of the nation's waters. Coastal condition has already been evaluated. During the next five years, EPA will sample the condition of lakes, large rivers, and wetlands. Then the process will be repeated to provide ongoing comparisons of the state of the waters and point to possible future action.

More information on Wadeable Streams Assessment: