More than half of the nation’s river and stream miles are in poor condition for aquatic life. That’s according to the first comprehensive survey of river health by the Environmental Protection Agency.
Data was collected from about 2,000 sites across the country from 2008-09, and then federal, state and university scientists analyzed the information to determine how well the waterways support aquatic life and how major stressors might be affecting them.
Denise Keener, director of EPA’s Office of Wetlands, Oceans and Watersheds, said 55 percent of stream and river miles are in poor condition.
“We find that nutrient pollution and degradation of habitat, things like erosion of soil and erosion of stream banks, are some of the primary reasons why we are seeing this poor water quality and poor biological condition,” she said.
Nutrient pollution, which is caused by high levels of nitrogen and phosphorous in the water, causes significant increases in algae, harming water quality, food resources and habitats. It also decreases oxygen needed by fish and other aquatic life.
Keener said the erosion caused a loss of riparian areas, those stretches of vegetation near river banks, that capture pollutants before they can enter the water.
Other threats to the waterways’ health are increased levels of mercury and bacteria. Nine percent of river miles have high levels of bacteria, while 13,000 miles of river have fish with mercury levels that might be unsafe for human consumption.
Keener noted that in general, a greater percentage of river and stream miles east of the Mississippi were in poorer health than to the west. The study looked at nine ecological sectors with most of Pennsylvania in the Southern Appalachian Region and the remainder in the Northern Appalachian Region.
“We’re looking at 65 percent of waters in the Southern Appalachian Region having poor biological condition, and in the Northern Appalachian Region, we see 57 percent in poor biological condition,” Keener said.
She said those conditions are dangerous for ecological communities from “diatoms (a common form of phytoplankton) all the way up to fish.”
Keener said the EPA is working with state agricultural agencies to reduce nutrient pollution by decreasing the levels of phosphorous and nitrogen that make it into the waterways.