National Water-Quality Assessment (NAWQA) Project

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Ecological Health in the Nation's Streams, 1993-2005

Report-USGS Circular 1391      Fact Sheet     Press Release     FAQs     Graphics and Tables


83 percent of assessed streams had at least one altered biological community

Assessments of stream health that are limited to a single biological community are likely to underestimate the effects of land and water use on stream health.



streamAnnual high or low streamflows were modified in 86 percent of the assessed streams

Natural fluctuations of flows are critical to stream health because they build and maintain physical habitats, influence physical and chemical characteristics of water, and provide important life-stage cues for aquatic organisms.


Unraveling the effects of multiple factors on stream health

Stream health is often reduced due to multiple factors--temperature, nutrients, or pesticides. Understanding the interacting natural and manmade factors that influence aquatic communities is essential to implementing effective management strategies to protect stream health.

Congressional Briefing Presentations

Daren Carlise (USGS),
Peter Ode (CA Department of Fish and Wildlife),
and David McKinney TN Wildlife Resources Agency

Additional NAWQA Ecological Publications

Assessment Tools

National Aquatic Database of Aquatic Bioassessment Data
Aquatic Sampling Protocols
Diatoms of the United States -A tool for Taxonomic Consistency
National Reference Site Database

Related Links

USGS Effects of Urban Development on Stream Ecosystems
USGS Real Time Water-Quality Data
USGS Real Time Streamflow Data
EPA National Aquatic Resource Surveys

Congressional Briefing Presentations

Natural Stream Ecosystem (PDF)
Natural Stream Ecosystem


Agricultural Stream Ecosystem (PDF)
Agricultural Stream Ecosystem


Urban Stream Ecosystem (PDF)
Urban Stream Ecosystem


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