About a third of US rivers contaminated with agricultural runoff

The Snake River flowing through Grand Teton National Park. Photo by Ansel Adams (courtesy of U.S. National Archives).

Ansel Adams

At least our rivers don’t light on fire anymore. Inspired by a well-publicized fire on the Cuyahoga River in 1969, the passage of the Clean Water Act in the US led to huge reductions in water pollution. Despite those positive strides, maintaining water quality requires ongoing attention. A new survey of streams and rivers, performed by the EPA, provides a greater sense of the scale of the challenge. While industrial pollution, like mercury, remains a concern, agricultural runoff, in the form of sediment and fertilizers, is now far more widespread.

Water quality monitoring is performed by states using a variety of methods, which can make it difficult to accurately compile the national picture. The US Environmental Protection Agency has started carrying out nation-wide surveys to provide consistent, standardized snapshots of water quality. Following on the heels of the 2006 Wadeable Streams Assessment, the EPA recently released a draft comprehensive survey of streams and rivers.

The legwork was carried out in 2008 and 2009 by 85 crews that visited 1,924 sites in the lower 48 states. The sites were selected at random using an algorithm that ensured a representative sample. At each site, crews evaluated the stream’s surroundings, inventoried the species present, and collected samples for chemical analysis.