Only 21 percent in "good" conditionThe U.S. Environmental Protection Agency (EPA) sampled around 2,000 rivers and streams in 2008-2009 and, after taking a few years to analyze and compile the data, they've released a draft version of the National Rivers and Streams Assessment 2008-2009 (pdf). What they found is pretty alarming: Only 21 percent of rivers and streams were deemed to be in "good" health, while 23 percent were rated "fair" and 55 percent got a "poor" grade.
Of the three major climatic regions (Eastern Highlands, Plains and Lowlands, and West) discussed in this report, the West is in the best biological condition, with 42% of river and stream length in good condition. In the Eastern Highlands, 17% of river and stream length is in good condition; in the Plains and Lowlands, 16% is rated in good condition.
There are various reasons for the bad shape the nation's rivers and streams are in. Nutrient pollution is a major cause, with phosphorus and nitrogen running off from agricultural and urban sources. There's also land development that can cause accelerated erosion and flooding (mostly through removing natural plant and tree cover).
In a statement, Nancy Stoner, Office of Water Acting Assistant Administrator at the EPA, said:
The health of our Nation’s rivers, lakes, bays and coastal waters depends on the vast network of streams where they begin, and this new science shows that America’s streams and rivers are under significant pressure. We must continue to invest in protecting and restoring our nation’s streams and rivers as they are vital sources of our drinking water, provide many recreational opportunities, and play a critical role in the economy.