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Oregon Study Finds Pesticides in River and Drinking Water

by aseligmann — last modified Jul 06, 2010 12:00 AM

A recent U.S. Geological Survey study reported that some pesticides discovered in Oregon's lower Clackamas River have made their way into municipal drinking water.


A recent U.S. Geological Survey study reported that some pesticides discovered in Oregon's lower Clackamas River have made their way into municipal drinking water.

The study, conducted from 2000-2005, detected 63 pesticide compounds in the lower Clackamas River and its tributaries. Fifteen of these pesticides, mostly herbicides, were detected in treated drinking water at levels that were not considered harmful. However three chemicals detected in the drinking water, including DEET, have no established health benchmarks. These findings "should send a strong signal that the river needs to be cleaned up," Oregon state officials said, according to a March 18, 2008 Oregonian article. In the same article a state toxicologist noted that little is known about the toxicity of mixtures of chemicals.

Some pesticide detections indicated risks for fish and other aquatic organisms. During storms, concentrations of certain insecticides spiked to levels that exceeded benchmarks designed to protect aquatic life in seven of eight tributaries as well as in the Clackamas River itself.

As in many rivers across the United States, the most frequently detected pesticides in the lower Clackamas system were the herbicides atrazine, simazine, metolachlor and diuron, and the insecticides diazinon and chlorpyrifos. In this study, high use herbicide ingredients such as those found in Roundup (glyphosate) and Crossbow (2,4-D & triclopyr) were also frequently detected. Altogether, the 51 currently used pesticides found included 33 herbicides, 15 insecticides and six fungicides.

The lower Clackamas basin encompasses urban, suburban, industrial, agricultural, and forestry land uses. The pesticides detected can be used in a variety of settings, making it difficult to pinpoint the sources contributing to the contamination. More than 90% of the pesticide contaminants are registered for use on crops and in nurseries; 57% are common ingredients in lawn and landscaping products; 45% may be used along roadsides and on other rights-of-way and 7% can be used on forests.

Lead scientist Kurt Carpenter observed that data collected from Oregon's new pesticide use reporting program will be too broad to help watershed managers who "could benefit from more detailed reports of which pesticides are being used and where."

 


NEWS STORIES

Study finds pesticides common in the lower Clackamas River, tributaries.
Scott Learn. The Oregonian, March 18, 2008.

USGS study finds pesticides in the lower Clackamas River mainstem and tributaries, and in samples of drinking water. [new release]
U.S. Geological Survey. March 18, 2008.

REPORT

Carpenter, KD et al. 2008. Pesticide occurrence and distribution in the lower Clackamas River basin, Oregon, 2000-2005. U.S. Geological Survey Scientific Investigations Report 2008-5027 http://pubs.usgs.gov/sir/2008/5027/