New information available on toxic chemicals in Yakima River

Washington State Department of Ecology

Department of Ecology News Release - April 27, 2010

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YAKIMA – A check-up of water quality conditions in the Yakima River watershed has identified additional sources of toxic contamination to surface waters, and confirmed that changes in agricultural practices have lessened the amount of pollution coming from irrigation runoff.

But there’s still more to be done for the river to meet state water quality standards.

The Yakima River Watershed Toxics Project examined streams, rivers and lakes from the headwaters near Snoqualmie Pass to where the river drains into the Columbia River at the Tri-Cities.

Washington Department of Ecology's report on toxic chemicals found in surface waters throughout the Yakima River basin is posted online.

The report found that while less soil sediment, DDT and related chemical compounds are making their way into the river through irrigation returns, pollution levels in the river or its tributaries still violate state water quality standards.

The study also identifies other sources of chemicals not previously studied by Ecology in the Yakima River watershed, such as polychlorinated biphenyls (PCBs), which were used in electrical transformers and switches.

“This new study has helped us to identify a path forward towards continued success,” said water quality specialist Ryan Anderson. “With that information we can expand the success we had cleaning up irrigation water, and now work with all of the communities in the watershed to help prevent these chemicals from getting into the water in the first place.”

Currently, the Yakima River doesn’t meet state standards for a range of chemical contaminants. They include DDT and other legacy pesticides, suspended soil sediments, turbidity (cloudy water), and PCBs. The standards are designed to protect human health for eating fish and to protect other aquatic life.

The latest report details results from samples taken in 2007-08 for pesticides and PCBs in tributary streams, irrigation returns and from permitted facilities that discharge to the river, such as wastewater treatment plants and fruit-processing houses. Stormwater runoff from the cities of Yakima, Union Gap and Ellensburg was also sampled and analyzed.

Past studies confirmed that pesticides are carried to the water when soil erodes, Anderson noted. And sampling of irrigation return drains has shown significant improvements over the last 15 years.

“Because so many farmers are using irrigation methods that reduce or prevent soil erosion, we’ve been able to reduce the amount of sediment and chemicals carried to the river. But we still have more work to do,” Anderson said.

Information from the new study will be used to augment existing efforts to clean up the river and achieve state water quality standards for a variety of parameters.

Improving water quality protects human health and benefits farming, fishing, recreation and other activities.

Some quick facts from the recent water quality study indicate:

Human health criteria for some pesticides (DDE, dieldrin, toxaphene) and PCBs are still not met in the Lower Yakima River and some tributaries and irrigation returns.
Despite significant reductions in soil erosion, irrigation returns continue to contribute turbidity and pesticides at levels that violate state water quality criteria in the lower Yakima River.
Controlling pollution sources to irrigation returns and urban stormwater runoff are important ways for reducing pollution to surface water.
To meet water quality criteria at the point of discharge, PCBs must be reduced in wastewater treatment plant discharges, and several pesticides must be reduced in fruit packer and vegetable processor discharges. Further testing on pesticides in treatment plant effluent is also needed.
Results from a first-time effort to characterize chemical contaminants in urban stormwater discharges to the Yakima River showed high levels of PCBs, sediment, and turbidity in runoff from the cities of Yakima, Union Gap and Ellensburg. This study also found pesticides in runoff from the cities of Yakima and Union Gap.

Earlier studies found some of these chemicals in fish living in the Yakima River and some of its tributaries. Since 1993, the state Department of Health had advised people to limit the amount of bottom fish they eat from the Lower Yakima River, due to high levels of DDT found in the tissue of those fish.

In 2006, Ecology collected and analyzed hundreds of Yakima River fish for toxic chemicals. A report on this study was released in 2007 and can be found online (See Chlorinated Pesticides, PCBs, and Dioxins in Yakima River Fish in 2006).

In 2009, state health officials updated the 1993 information and determined that due to successful erosion control improvements and reduced DDT levels, they could drop advisories to limit meals from certain Yakima River fish species. The recent data on PCBs, however, resulted in new advice on eating common carp from the Yakima.

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Media contacts:
Joye Redfield-Wilder, communications manager, (509) 575-2610; jred461@ecy.wa.gov
Ryan Anderson, water quality specialist, (509) 575-2642; rand461@ecy.wa.gov
Jane Creech, water quality specialist, (509) 925-2557; jton461@ecy.wa.gov

For more information:

Project study plan: www.ecy.wa.gov/biblio/0703107.html
General information about water quality cleanup projects: www.ecy.wa.gov/programs/wq/tmdl/
Department of Health fish advisory information: www.doh.wa.gov/AboutUs/ProgramsandServices/EnvironmentalPublicHealth/EnvironmentalHealthSafetyandToxicology/FishAdvisories.aspx
Yakima River Pesticides and PCBs Total Maximum Daily Load: Volume 1. Water Quality Study Findings: www.ecy.wa.gov/biblio/1003018.html
Chlorinated Pesticides, PCBs, and Dioxins in Yakima River Fish in 2006: Data Summary and Comparison to Human Health Criteria: www.ecy.wa.gov/biblio/0703036.html