Most U.S. Rivers, Streams in Poor Condition for Aquatic Life

Thousands of stream and river miles across the country under ‘significant pressure’: EPA

In its first comprehensive survey looking at the health of thousands of stream and river miles across the country, the U.S. Environmental Protection Agency (EPA) has found more than half – 55 percent – in poor condition for aquatic life.

The 2008-2009 National Rivers and Stream Assessment reflects the most recent data available on the condition of the water resources, EPA said.

[Does that mean the significant degradations that have occurred in the past 5 years not yet taken into account? Moderator]

“The health of our Nation’s rivers, lakes, bays and coastal waters depends on the vast network of streams where they begin, and this new science shows that America’s streams and rivers are under significant pressure,” said Office of Water Acting Assistant Administrator.

The data was collected by EPA, state and tribal researchers from about 2,000 sites across the country.

National Rivers and Stream Assessment. Biological condition of the nation’s rivers and streams, based on the Macroinvertebrate Multimetric Index (EPA/NRSA).

Indicators Evaluated for NRSA

Biological Indicators

• Benthic macroinvertebrates
• Periphyton (algae)
• Fish community

Chemical Indicators

• Phosphorus
• Nitrogen
• Salinity
• Acidity

Physical Indicators

• Streambed sediments
• In­stream fish habitat
• Riparian vegetative cover
• Riparian disturbance

Human Health Indicators

• Enterococci (fecal indicator)
• Mercury in fish tissue

The following are excerpts from EPA report:

Runoff Contaminated by Fertilizers

• Nitrogen and phosphorus are at excessive levels. 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.

Decreased Vegetation Cover and Increased Human Disturbance

• Streams and rivers are at an increased risk due to decreased vegetation cover and increased human disturbance. 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.

[Whopping] Increase in Bacteria Levels.

• Increased bacteria levels. High bacteria levels were found in nine percent of stream and river miles making those waters potentially unsafe for swimming and other recreation (samples exceed an enterococci threshold level for protecting human health.)

Increased Mercury Levels

• Increased mercury levels. More than 13,144 miles of river lengths (streams were not evaluated) 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.

NRSA Sample Sites

National Rivers and Stream Assessment Sample Sites.

Related Links

• Death by Lethal Pollution October 16, 2007
• Index of Human Impact on Nature

“Troubled Waters” by U.S. PRIG