Urban runoff main source of pesticide in California rivers

Feb 9, 2010

Researchers who studied runoff from agriculture, sewage treatment plants and urban neighborhoods found that the main source of pesticide concentration was from urban run-off, according to an article published in the Daily Californian. Portions of the American River and San Joaquin River contain pesticide levels high enough to kill some invertebrates, such as gadflies and mayflies.

"On the source side of things, urban run-off consistently has pyrethroids at levels that are toxic to some organisms," the story quoted Donald Weston, a UC Berkeley biology professor and co-author of the study. The study was published in the journal Environmental Science & Technology.

The researchers found that nearly all residential runoff samples had pyrethroid levels that were toxic to the test organism, Hyalella azteca. Pyrethroids are found in many common household insecticides - such as Raid.

Weston told the Californian that the prevalence of pyrethroids in household insecticides was due in part to a ban on organophosphate insecticides in such products. Pyrethroid use has increased about three-fold over the last 10 years, he said.

By Jeannette E. Warnert
Author - Communications Specialist

Attached Images:

Urban water runs into storm drain.