Half the length of U.S. streams and rivers in poor condition

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% is 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.

The results, released Tuesday, found that of the three climatic regions discussed in the report, the West -- with its large swaths of undeveloped land -- was in the best shape: 42% of its river and stream length was in good ecological condition, 27% in fair condition and 30% in poor condition.

In the eastern highlands, 63% of river and stream miles were in poor shape, while in the Plains and lowlands regions (roughly the country’s midsection and much of the South), 58% fell into that category.

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.