The study found that "more than a quarter of rivers and streams registered high nitrogen levels and 40 percent had too much phosphorous," Malewitz notes. "Such nutrient pollution sparks algae growth, eroding food supplies and depriving aquatic species of oxygen. More than a quarter of rivers and streams are particularly prone to flooding, pollution and erosion because of a dearth of vegetation cover. Nine percent of waters tested positive for high bacteria levels, making them not fit for swimming. Fish in more than 13,000 of miles of water carried high levels of mercury."
Some farm groups are concerned about the way the study was conducted, reports Agri-Pulse, a Washington newsletter. The issues raised by the assessment are “incongruent with what’s going on out there in U.S. agriculture,” including enhanced conservation programs, precision technology and other advances that are reducing farm nutrient runoff, said Don Parrish, of the American Farm Bureau Federation. He said EPA is comparing water samples taken from a dozen or so ecological regions around the country to the “least disturbed” sites in each region.
"Some level of human impact on water resources is a given and that using the very best of today’s conditions as a yardstick sets everyone up for failure," Parrish said. The “least-disturbed standard,” which can also vary from region to region, is an “unrealistic approach that sets unreasonably high expectations. There are far more appropriate standards that EPA could have selected.”
The worst area was "the Coastal Plains region, stretching from Eastern Texas to Florida and along much of the Atlantic coast," Malewitz notes. "There, 71 percent of waters were deemed poor." The area includes the lower Mississippi River. (Read more) For states' measurements of water quality in specific streams, click here.