Water Quality Improvement Project
Yakima Watershed Area:
Toxics

Water quality testing found toxic chemicals in the Yakima River and some of its tributaries. Most of these chemicals are banned pesticides or PCBs (polychlorinated biphenyls) that are no longer used. We are working with local government and citizens to clean up these persistent “legacy” pesticides.

Water quality issues

The Yakima River originates in Kittitas County, located on the east side of the Cascade Mountains near Snoqualmie Pass. The confluence of the Yakima and Naches Rivers (one of its tributaries) at the city of Yakima divides the Yakima River into "upper" and "lower" portions.

The lower Yakima River basin is one of the most intensively farmed and irrigated areas in the United States. Past studies show that some legacy pesticides get into the water when contaminated soil erodes and enters the water. Some of these compounds were also found in fish living in the Yakima River and some of its tributaries. See study area map.

What we have done

We conducted a study on water quality conditions in the Yakima River watershed in 2006. Although the study found additional sources of toxic water contamination to the surface waters, the study also determined that changes in agricultural practices have reduced the amount of pollution coming from irrigation runoff. While some Yakima River fish still have pesticides in their flesh, the levels are much improved (reduced) compared to previous years. This reduction in pesticide levels in fish tissue allowed the Washington Department of Health to drop its advisory on DDT in most of the lower Yakima River fish species.

Farmers and other land users in the watershed implemented existing total maximum daily loads (TMDLs) that may have helped some of the water quality problems. The Roza Sunnyside Board of Joint Control and Kittitas County Water Purveyors adopted water quality policies that reduce the amount of polluted runoff entering into tributaries of the Yakima River. Many agricultural operations adopted practices that prevent or reduce their impact to streams.

The technical study for the Yakima Watershed Toxics Reduction Project was published in 2010.

In 2016, we convened a stakeholder work group to help decide on the best path to clean up the river most quickly. Since most of the pollution is still in lower Yakima Valley, the initial focus of the work group will be reducing lower Yakima Valley nonpoint toxic pollution sources. This work group will work with lower valley community groups to continue to reach water quality goals in the watershed.

Status of the project

Based on the findings and recommendations in the Yakima Watershed Toxics Reduction Project technical study, we are developing a new water quality improvement project that includes a new evaluation of current levels of DDT in the lower Yakima River valley, sets human health clean-up targets for DDT, and lays a path to achieve these targets.

We will continue to monitor sediments and turbidity as well as legacy pesticides to measure the progress of other water quality improvement project work. These efforts will help bring the watershed into compliance with state water quality standards.

Recommendations

Since a high percentage of the pollution in the lower Yakima watershed still comes from soil erosion from farms, growers who have not made changes in irrigation practices and water management need to do so now. Sediment from farmland, including pesticides that adhere to the sediment particles, must be further reduced in major drains and tributaries to meet targets outlined in the Ecology report. Other sources will be assigned load reduction targets as part of the Yakima Watershed Toxics Reduction Project.

Why this matters

Toxic chemicals, which are persistent chemicals in the environment, are a growing concern for the state. They can contaminate the food (fish, shellfish, etc.) that people may eat. In the Yakima River valley, these chemicals are mostly from agricultural pesticides and industrial pollution. They can be found in our air, water, soil, and wildlife. And, they are showing up in people's bodies, which may lead to health problems.

Technical information

Unless otherwise specified, the following document are Ecology publications.

Quality Assurance Project Plan - Chlorinated Pesticides, PCBs, and Dioxins in Yakima River Fish - 2006: Assessing Progress Toward TMDL Targets and Updating the Fish Consumption Advisory
https://fortress.wa.gov/ecy/publications/SummaryPages/0603111.html

Chlorinated Pesticides, PCBs, and Dioxins in Yakima River Fish in 2006: Data Summary and Comparison to Human Health Criteria
https://fortress.wa.gov/ecy/publications/SummaryPages/0703036.html

Quality Assurance Project Plan- Yakima River Chlorinated Pesticides, PCBs, Suspended Sediment, and Turbidity Total Maximum Daily Load Study
https://fortress.wa.gov/ecy/publications/SummaryPages/0703107.html

Yakima River Pesticides and PCBs Total Maximum Daily Load: Volume 1: Water Quality Study Findings
https://fortress.wa.gov/ecy/publications/SummaryPages/1003018.html

Related information

Unless otherwise specified, the following document are Ecology publications.

New information available on toxic chemicals in Yakima River (Ecology news release)
www.ecy.wa.gov/news/2010news/2010-088.html

Yakima River Watershed Toxics Study
https://fortress.wa.gov/ecy/publications/SummaryPages/0610069.html

Frequently Asked Questions: Yakima River Watershed Toxics Study: Progress Update
https://fortress.wa.gov/ecy/publications/SummaryPages/0910088.html

Fish Consumption Advisories for Yakima River (WA Department of Health)
www.doh.wa.gov/CommunityandEnvironment/Food/Fish/Advisories.aspx#YakimaRiver

WRIA 37: Lower Yakima Watershed Information (Water web site)
www.ecy.wa.gov/water/wria/37.html

WRIA 38: Naches Watershed Information (Water web site)
www.ecy.wa.gov/water/wria/38.html

WRIA 39: Upper Yakima Watershed Information (Water web site)
www.ecy.wa.gov/water/wria/39.html

 

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Last updated March 2017
  Water resource inventory area (WRIA) 37 map, Washington State.

PROJECT INFO

Location:
WRIA:
#37 (Lower Yakima)
#38 (Naches)
#39 (Upper Yakima)

Counties:
Benton
Kittitas
Klickitat
Yakima

Water-body Name:
Yakima River

Parameter:
Toxics

# of TMDLs: ---

Status:
TMDL under development

Contact Info:
Jane Creech
Phone: 509-454-7680
Email:  Jane.Creech@ecy.wa.gov

Central Region
Department of Ecology
1250 West Alder Street
Union Gap, WA 98903-0009