More than half of the country’s rivers and streams are in poor biological health, unable to support healthy populations of aquatic insects and other creatures, according to a new nationwide survey released Tuesday. The Environmental Protection Agency sampled nearly 2,000 locations in 2008 and 2009 — from rivers as large as the Mississippi River to streams small enough for wading.

Even some of the most remote mountain lakes in the northern hemisphere have been affected by the long reach of human pollution, according to researchers who found traces of nitrogen compounds in more than 75 percent of the lakes they surveyed in Europe and the Rocky Mountains of North America.

When Clarence Aragon began managing the half-century-old Mora Mutual Water and Sewer Association 12 years ago, he thought he was helping the environment. Hundreds of households around Mora, N.M.

Colorado is proposing to control nutrients in water for the first time, but a Durango attorney says the rules are too complicated, based on weak science and exorbitantly expensive. Jeff Kane of Maynes, Bradford, Shipps & Sheftel brought Southwestern Water Conservation Dis

Biologically diverse streams are better at cleaning up pollutants than less rich waterways, and a University of Michigan ecologist says he has uncovered the long-sought mechanism that explains why this is so. Bradley Cardinale used 150 miniature model streams, which use recirculating water in flumes to mimic the variety of flow conditions found in natural streams.

Elevated concentrations of nitrogen and phosphorus, nutrients that can negatively impact aquatic ecosystems and human health, have remained the same or increased in many streams and aquifers across the United States since the early 1990's, according to a new national study by the U.S. Geological Survey.

The U.S. EPA is planning to impose limits on phosphorus and nitrogen in Florida waters that will be the first federal standards for nutrient pollution in the waters of a state. This action would potentially have consequences for other states.

Airborne nitrogen pollution from vehicle exhaust and farm fertilizer is turning algae in the alpine lakes of Rocky Mountain National Park into junk food for fish, a study says. A similar phenomenon is occurring in Sweden and Norway, according to the study of about 90 high-elevation lakes set to be published in the journal Science on Friday.