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The Story of Our Nation’s Waters

Ellen Gilinsky
U.S. Environmental Protection Agency

The inland waterways and coastlines of the United States are critically important to commerce, agriculture, public health and recreation. These activities, however, often adversely affect the nation’s rivers and coasts through water diversion, dams, excess nutrients, and fuel spills. Poor water quality will ultimately have a deleterious impact on downstream environments and public health. Maintaining or restoring the integrity of the nation’s water quality is at the heart of the Clean Water Act (CWA) of 1972. Most bodies of water extend across state lines yet the CWA requires each state to determine and set its own water quality standards, . The resulting differences in standards and methods among states makes it impossible to compare the water quality status of one state against another, even when they share the same body of water. To resolve this problem, the U.S. Environmental Protection Agency (EPA) began the National Aquatic Resource Surveys (NARS) in 2005 to evaluate regional water quality across the 48 contiguous states. 

Dr. Ellen Gilinsky, senior policy advisor in the U.S. EPA’s Office of Water, kicked off the Metcalf Institute’s 2013 lecture series on Monday, June 10 at the University of Rhode Island Graduate School of Oceanography with her talk, “The Story of our Nation’s Waters.” She discussed how NARS assess the nation’s water quality by applying two broad questions: what are the current conditions of our waterways, and what should they be? She also conveyed what NARS has found about various waterways in different parts of the country over five-year evaluation cycles. Dr. Gilinsky concluded by describing the ways that EPA’s findings aid in establishing national and state guidelines, and how the public can become more aware of their local and regional watersheds.

To evaluate the health of U.S. streams and rivers, lakes, and coastal waters, the NARS program–working with state and local governments and universities–utilizes probabilities to statistically evaluate the water quality of 1000 randomly selected sites across the country. Dr. Gilinsky noted that of the 1000 sites, 50% are sites from previous surveys and 10% are revisited from a previous survey cycle. Researchers measure biological (benthic macroinvertebrates, plants, and fish communities), chemical, and physical characteristics within each site. These parameters are combined to determine a “reference condition,” or the least disturbed condition expected in a geographic region. Water quality of the other sites in a region is then rated in comparison to the reference condition, with the top 25% of those sites receiving a “good” rating, the middle 70% receiving a “fair” rating, and the bottom 5% receiving a “poor” rating.

Dr. Gilinsky showed that the NARS results identified three primary water quality stressors for the nation’s streams and rivers: high nutrient levels (excess nitrogen in 40% of sites and excess phosphorus in 27% of sites), decreased vegetative cover, and increased human disturbance such as development. The NARS statistical probabilities indicated that 55% of the nation’s rivers and streams and 22% of lakes are subjected to these primary stressors and therefore are likely to be considered biologically poor. These results were mixed when compared with the 2004 NARS survey, with 7% fewer streams rated “good,” but 19% with lower phosphorous loads. On the upside, Dr. Gilinsky showed that U.S. coastal waters exhibited an improving trend since the last coastal survey, with only 6% of coastal waters likely to be considered poor and 36% in fair condition.

The results from NARS are made available to public, state, tribal, and federal agencies to help them establish guidelines for improving each region’s water quality. An additional goal of NARS is to increase public understanding of their local watersheds, and the impact that human activities have. Towards this end, Dr. Gilinsky mentioned that the EPA has developed a phone app that shows people the water quality in a specified area. More information about this app and a link to download it can be found at:

Lecture Summary prepared by Al Nyack, Ph.D.

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