There’s good news and bad news, EPA says, when it comes to the condition of the nation’s rivers and streams. Well, mostly bad—according to the latest National Rivers and Streams Assessment, 55% of river and stream miles are too impaired to support healthy aquatic populations. Another 23% are in fair condition, and only 21% are in good condition to support healthy biological communities.
The survey, from 2008 – 2009, the most recent information available, also lists the main causes of impairment. Perhaps the good news from an erosion control perspective is that sediment is no longer the worst problem facing our waterways. The survey shows 15% of river and stream miles have excess levels of streambed sediments.
Nutrients are the main problem; 40% of rivers and streams have too much phosphorus and 27% too much nitrogen. Poor vegetative cover affects 24%, and human disturbance near the banks 20%—both of which could lead to increased erosion. Bacteria affect 9% of streams, and excess levels of mercury were found in 13,000 stream miles nationwide.
Overall, 7% fewer stream miles are in good condition compared to the 2004 survey, and phosphorus impairment has increased significantly, but 9% more stream miles are in good condition for nitrogen this time around. Fish habitat and riparian disturbance also seem to be improved from the 2004 survey.
The complete draft report is available here.