More than half of the nation’s rivers and streams are in poor health, according to a comprehensive survey by the Environmental Protection Agency.
The 2008-09 National Rivers and Stream Assessment reflects the most recent data available, and is part of EPA’s expanded effort to monitor U.S. waterways and to gather scientific data on the condition of the country’s water resources, according to a news release.
- [highlight color=”eg. yellow”]Nitrogen and phosphorus are at excessive levels.[/highlight] Twenty-seven percent of the nation’s rivers and streams have excessive levels of nitrogen, and 40 percent have high levels of phosphorus. Too much nitrogen and phosphorus in the water-known as nutrient pollution-causes significant increases in algae, which harms water quality, food resources and habitats and decreases the oxygen that fish and other aquatic life need to survive. Nutrient pollution has impacted many streams, rivers, lakes, bays and coastal waters for the past several decades, resulting in serious environmental and human health issues, and impacting the economy.
- [highlight color=”eg. yellow”]Streams and rivers are at an increased risk due to decreased vegetation cover and increased human disturbance.[/highlight] These conditions can cause streams and rivers to be more vulnerable to flooding, erosion, and pollution. Vegetation along rivers and streams slows the flow of rainwater so it does not erode stream banks, 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 vegetative cover.
- [highlight color=”eg. yellow”]Increased bacteria levels.[/highlight] High bacteria levels were found in nine percent of stream and river miles making those waters potentially unsafe for swimming and other recreation.
- [highlight color=”eg. yellow”]Increased mercury levels.[/highlight] More than 13,000 miles of rivers have fish with mercury levels that may be unsafe for human consumption. 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.
The EPA plans to use the data to inform decision making about addressing critical needs around the country for rivers, streams, and other water bodies. This comprehensive survey also will help develop improvements to monitoring these rivers and streams across jurisdictional boundaries and enhance the ability of states and tribes to assess and manage water quality to help protect our water, aquatic life, and human health, according to the release. Results are available for a dozen geographic and ecological regions of the country.