Among the principal causes of nutrient pollution in the nation’s rivers are urban storm-water runoff, soil erosion, and animal manure and fertilizers in runoff from farms. Wikimedia Commons/U.S. Department of Agriculture, Natural Resources Conservation Service
More than half of the nation’s rivers and streams are in poor condition, according to a new report from the U.S. EPA
May 7, 2013—A large percentage of the nation’s rivers and streams are insufficiently able to support aquatic life as a result of runoff, agricultural practices, fossil fuel pollution, and inadequate sewer systems, according to a report released in March by the U.S. Environmental Protection Agency (EPA). The EPA conducted what agency officials call an unprecedented survey of the 1.2 million mi of rivers and streams in the continental United States and found that the waterways in 55 percent of those miles are in poor shape, the worst conditions being in the northeastern part of the country.
The agency’s assessment was conducted during the summers of 2008 and 2009 and saw more than 85 field crews collecting samples at 1,924 river and stream sites around the country. The crew members tested waterways ranging in size from small streams to the Mississippi River and collected data on sediment levels, adjacent vegetation cover, the effects of human activity, and habitat quality for fish and other organisms, all of which are strong indicators of river and stream health.
The survey found that 9 percent of the nation’s river and stream miles contain levels of bacteria of the genus Enterococcus that are potentially harmful to human health, that 27 percent have excessive levels of nitrogen, and that 40 percent have excessive levels of phosphorus. EPA officials cited pollution from urban and agricultural areas as major causes, but some environmentalists place much of the blame on agriculture and argue that weak federal regulations and risky farming practices have created a unique set of challenges for the nation’s waterways.
“Sadly, it’s not surprising. It is a trend that’s been going on for a while,” says Don Carr, a senior adviser for the Environmental Working Group, a nonprofit environmental health research and advocacy organization headquartered in Washington, D.C. “There are a lot of pollutants that come from municipalities and a lot of pollutants that come from industrial work, but the largest source of water pollution in America is agriculture—and industrial agriculture at that.”
The EPA detailed its findings in a 110-page report entitled National Rivers and Streams Assessment 2008–2009: A Collaborative Survey. The report outlines the levels of pollution in rivers and streams, its probable sources, and potential remedies. The field crews documented the physical characteristics of the nearly 2,000 sites; examined the presence and condition of fish, macroinvertebrates, and algae; and collected water samples that were tested for phosphorus and nitrogen and for salinity and acidity levels. They also conducted tests to measure bacteria levels and detect the presence of mercury in fish tissue.
The researchers found that high levels of nitrogen and phosphorus—a phenomenon known as nutrient pollution—were causing excessive algal growth in many areas. This in turn was impairing overall stream health and decreasing the amount of oxygen available to fish and other organisms.
EPA officials attributed most of the high phosphorus and nitrogen levels in the waterways to manure and fertilizer from farms, soil erosion, storm-water runoff from rooftops and pavement in cities and towns, and wastewater treatment systems that fail to remove sufficient levels of the pollutants before discharging the water.
The survey showed that pollutants can easily enter waterways in certain areas because of a diminished vegetation cover, often the result of human activity. Twenty-four percent of the river and stream miles included in the study were deemed to be in poor condition because of insufficient vegetation cover for capturing polluted rainwater, preventing erosion, and maintaining healthy water temperatures.
EPA officials say the federal government can markedly reduce waterway pollution and prevent contamination by increasing funding to states for initiatives to improve drinking water and wastewater infrastructure, restore polluted rivers and streams to health, and enforce limits on nutrient discharge by industrial and municipal sources.
William F. Hunt III, Ph.D., P.E., D.WRE, M.ASCE, an associate professor at North Carolina State University, says companies and governments in urban areas can use such control measures as wet detention basins, storm-water wetlands, rain gardens, and permeable pavement technology to capture storm water before it makes its way into rivers and streams. He says remedial options are plentiful in places that have unused land for water retention but that there are fewer solutions in dense urban areas.
“It’s all about development and what the political will is in a community, and if there’s simply available space,” says Hunt, who works in the biological and agricultural engineering department at North Carolina State and heads a research group that focuses on storm-water engineering. “If a watershed is built out and you don’t have room, you can make some improvements in the streams and in the public right-of-way, but you usually need to have a fair amount [of space] to have a noticeable improvement made.”
While Hunt calls for urban storm-water solutions, Carr believes more could be done on the agriculture side. He would like to see more small- and large-scale farmers take advantage of precision application and Global Positioning System technologies to improve growth while reducing nutrient use. Carr also wants tighter federal regulations on farms under the Clean Water Act and contends that government subsidies have taken much of the risk out of farming, leading many mass producers to plant crops along stream banks and in highly erodible places without fear of penalties. “When you have point-source [pollution]—like in a city when you have a pipe coming out of a wall and some type of toxic goop coming out of it—that’s something the EPA can prosecute and fine,” he says. “But non-point-source pollution, which is what comes off crop fields, is not regulated, and there is no penalty for anyone who allows it to keep happening.”