Data from 2008 through 2013 will serve as baseline for future monitoring; pesticides, certain metals warrant more study, DEQ says A newly released study from the Oregon Department of Environmental Quality’s Laboratory and Environmental Assessment Program shows that toxic chemicals ranging from pesticides to metals are present in all water basins of the state, with some monitoring sites showing levels above state criteria or benchmarks for human health and aquatic life.

DEQ’s Statewide Water Quality Toxics Assessment Report is available on DEQ’s water quality monitoring website at The study is the first statewide assessment of toxics in water across Oregon. It is the result of more than five years of data that DEQ collected from 177 monitoring sites throughout the state from 2008 to 2013. DEQ visited most sites three times and analyzed water samples for more than 500 different chemicals.

The samples came from large rivers, small streams and coastal estuaries. DEQ looked for a wide range of chemicals including: industrial solvents; PCBs; metals such as arsenic, lead, copper and cadmium; flame retardants; current-use and now-banned (legacy) pesticides; combustion byproducts and consumer product constituents such as acetaminophen and codeine. “This study helps provide the baseline data we need to conduct future water toxics monitoring and to investigate areas that may need additional work done,” said Aaron Borisenko, manager of the lab’s Water Quality Monitoring Program. DEQ detected 128 of the 500-plus chemicals it looked for. Most chemicals were at very low concentrations and within applicable criteria or benchmarks for environmental and human health. The largest variety of chemicals detected was in the Willamette River and Hood River basins, both areas containing population centers as well as agricultural and industrial activities.

Several key findings:

• Detections of current-use pesticides occurred in all basins, often as mixtures and at times at levels above aquatic life benchmarks set by the U.S. Environmental Protection Agency. The herbicide diuron was detected in all but one of the 15 basins examined.

• Legacy pesticides – those pesticides such as DDT and dieldrin that are no longer produced or are banned – are present in water samples, frequently at levels above state human health criteria.

• The pollutant metals copper and lead are present at levels above state aquatic life criteria throughout the state, but mostly in the populated areas of the Willamette Basin.

• Flame retardant chemicals, which can cause cancer, were detected in both urban and rural areas.

• Arsenic and inorganic arsenic was measured at levels above state human health criteria, mainly in Eastern Oregon and in Oregon’s coastal estuaries.

• Combustion byproducts known as polycyclic aromatic hydrocarbons, some which can also cause cancer, were detected at levels above state human health criteria at several locations.

• The Willamette and Hood basins had the most samples with at least one chemical over a criteria or benchmark for human or aquatic health.


DEQ will use information from this study to refine further monitoring at existing sampling sites and to identify new locations for toxic monitoring.

Beginning this year and through 2019, DEQ will collect toxics samples each year in specific geographic areas. This effort will begin later this year in the North Coast, Umpqua, Rogue and Klamath basins.

In addition, DEQ has identified several geographic areas in the state that will require follow-up sampling. These may include the Mid-Coast and Hood basins. DEQ also may further investigate the occurrence and source of inorganic arsenic and chlorinated pesticides in Oregon’s coastal estuaries. DEQ is also considering conducting water quality monitoring of lakes across the state, in conjunction with EPA’s National Lakes Assessment in 2017, as well as additional sampling with the lab’s biomonitoring program.

The bio-monitoring investigation will be limited in scope initially but may provide insight into effects on biological communities from low-level toxics on the environment, explained Lori Pillsbury, the study’s author.



Lori Pillsbury, Water Quality Monitoring Program, Laboratory and Environmental Assessment Program, Hillsboro, 503-693-5735

Aaron Borisenko, Water Quality Monitoring Manager, Laboratory and Environmental Assessment Program, Hillsboro, 503-693-5723