On September 11, 2014, the U.S. Geological Survey (USGS) announced results of a 20-year study of pesticide occurrence in rivers and streams in the United States. For two periods—1992 to 2001 and 2002 to 2011—the study compared the percentage of stream and rivers being monitored nationwide that contained pesticides at levels above those considered unhealthy for aquatic life. The study looked at streams in agricultural areas, urban areas, and areas with a mix of those land uses.
According to the study’s synopsis, “the proportions of assessed streams with one or more pesticides that exceeded an aquatic-life benchmark were very similar between the two decades for agricultural (69% during 1992−2001 compared to 61% during 2002−2011) and mixed-land-use streams (45% compared to 46%). [The proportion of] urban streams, in contrast, increased from 53% during 1992−2011 to 90% during 2002−2011….” Pesticide levels “seldom exceeded human-health benchmarks,” according to the USGS news release on the study.
The study is “Pesticides in U.S. Streams and Rivers: Occurrence and trends during 1992-2011,” published 9/11/14 online in the journal Environmental Science and Technology. A link to the study and additional information–including data, other reports, and maps–are available online at http://water.usgs.gov/nawqa/pnsp/pubs/pest-streams/.
Source: 20-Year Study Shows Levels of Pesticides Still a Concern for Aquatic Life in U.S. Rivers and Streams, U.S. Geological Survey News Release, 9/11/14.