86% of U. S. Rivers are 'Impaired', Says New Study
Most Rivers in the United States no longer flow the way they're supposed to flow, and that's changing the mix of fish and other organisms that call them home, according to a new study.
The most extensive study ever done of changes in river flows across the United States is a wake-up call about the state of American waterways.
Scientists with the U.S. Geological Survey (USGS) examined flow patterns of 2,888 river locations and compared what they found with the flows they'd expect to find under natural conditions. They focussed on changes in the magnitude of flows – the highs and lows that are so crucial to giving river creatures the habitats and life-cycle cues they need to survive.
What ecologist Daren Carlisle and his colleagues found is nothing short of a wake up call to make the restoration of river flows a high priority. Flows were altered in nearly nine of ten river segments, and compared with eight other variables – including water temperature, nitrogen and phosphorus pollution, and the loss of riverside land to farming or urban uses – stream-flow alteration was the primary predictor of a river's biological integrity.
The study appeared in the online version of Frontiers in Ecology and the Environment, a journal of the Ecological Society of America.