One in four U.S lakes is in fair or poor condition

New analysis from the Environmental Protection Agency shows four of every 10 U.S. lakes are in fair or poor condition. The report is the first from EPA using consistent criteria to evaluate lakes; it reveals that man-made impoundments tend to be in worse condition than natural lakes. The findings were "based on a review of indicators for physical, chemical, and biological measures of water quality; condition of lakeshore and shallow water habitat; and ability to support selected recreational uses," the Society of Environmental Journalists reports.

The investigation analyzed more than 1,000 lakes in the lower 48 states that were selected to represent the over 50,000 lakes in the contiguous U.S. Individual findings for specific lakes were not released, but the EPA report groups lakes into nine eco-regions. "Ninety-one percent of the lakes in the Upper Midwest were in good biological condition, compared to just five percent in the Northern Plains," SEJ reports. "Recreational conditions were by far the best in the Western Mountains and the Northern Appalachians, and the worst in the Northern Plains and Temperate Plains."

Half the lakes are home to fish whose flesh contains health-threatening concentrations of mercury, and more than one-quarter were found to potentially pose a threat from algal toxins. Indiana, Michigan, Minnesota, Oklahoma, Texas and Wisconsin had enough lakes measured to provide state-level data. (Read the SEJ TipSheet)