The news from a comprehensive national survey of river and stream health is not good: only about a fifth of the length of America's rivers and streams is in good biological condition, while 55% are in poor shape. The survey, which analyzed water samples taken in the summers of 2008 and 2009 at more than 1,900 randomly selected sites, was coordinated by the U.S. Environmental Protection Agency. Excessive nitrogen and phosphorus levels, sedimentation and denuded riverbanks were among the leading problems. Unsafe bacteria levels were found in 9% of river and stream miles, and potentially unsafe levels of mercury were detected in fish in more than 13,000 miles of rivers across the country.
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