Over 50 Percent of U.S. Rivers Are In Poor Health, Says A Newly Released EPA Survey

The U.S. Environmental Protection Agency has finally released the most recent data on the health of about 2,000 rivers and streams from across the country – and the results aren’t pretty.

The New River originates in Mexico and flows into the United States through Calexico, California. The river eventually meets up with the Salton Sea, a large inland sea. The New River is reported to be the most polluted river flowing into the U.S. from Mexico, says the California Report. Photo courtesy of the California Report.

States and tribes participated in the data collection, and found that 55 percent of the country’s rivers and streams are in poor condition based on their ability to support life.

The information was published in a collaborative survey report called the 2008-2009 National Rivers and Streams Assessment. The report looked at random samplings from river systems as large as the Mississippi River to as small as mountain headwater streams.

The report looked at how major stressors – both chemical and physical – are affecting these aquatic systems over time.

Chemical stress factors on the rivers and streams included excessive levels of nitrogen, phosphorus, and mercury.

To begin with, the report showed that 28 percent of the country’s rivers and streams had excessive levels of nitrogen, and 40 percent had high levels of phosphorus.

Known as nutrient pollutants, the EPA explains that too much nitrogen and phosphorus in water can cause significant increases in algae that can harm water quality, food resources, habitats, and decrease the oxygen that fish and other aquatic life need to survive.

Another issue of concern for human health in the report was mercury, which the EPA said was found in fish across about 13,000 miles of rivers. The agency expressed concerns, saying that the mercury levels could be in many cases “unsafe for human consumption.”

The EPA further added that, “For most people, the health risk from mercury by eating fish and shellfish is not a health concern, but some fish and shellfish contain higher levels of mercury that may harm an unborn baby or young child’s developing nervous system.”

In addition, the agency found high levels of bacteria in nine percent of river and stream miles, making those waters “potentially unsafe for swimming and other recreation.”

Beyond the chemical and bacterial stresses on the rivers and streams, there’s also the stress caused by human activity, including the degrading of riverbank (riparian) vegetation resulting in increased streambed sediment.

The EPA explained that “these conditions can cause streams and rivers to be more vulnerable to flooding, erosion, and pollution,” adding that vegetation along rivers and streams slows the flow of rainwater so it doesn’t erode stream banks.

The vegetation also “removes pollutants carried by rainwater and helps maintain water temperatures that support healthy streams for aquatic life. Approximately 24 percent of the rivers and streams monitored were rated poor due to the loss of healthy cover,” added the agency.

The damage to vegetation also affected sediment distribution. The EPA found “excess levels of streambed sediment” in 15 percent of the rivers and streams which had a significant impact on biological conditions.

The agency says that excess levels of streambed sediments can smother the habitat where many aquatic organisms live and breed, adding that “poor biological condition is 60 percent more likely in rivers and streams with excessive levels of streambed sediments.”

The EPA looked at the biological conditions in three major climatic regions – the Eastern Highlands, the Plains and Lowlands, and the West – for the survey report.

The report found that the West had the best biological conditions, with 42 percent of rivers and streams in good health. In the Eastern Highlands, 17 percent of the rivers and streams were found in good condition. And, in the Plains and Lowlands, 16 percent were rated in good condition. 

The goal of the survey was to determine the extent to which rivers and streams across the country can support healthy biological conditions and what major stress factors are affecting them.   

The EPA says that reducing nutrient pollution and improving habitat will significantly improve the biological health of rivers and streams across the country.

The report recommends the need to address sources of pollution – including runoff from urban areas, agricultural practices and wastewater – to create healthier waters.

Additional Resource

• EPA Fact Sheet: National Rivers & Streams Assessment 2008-2009

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