Water Quality Improvement Project
Upper Yakima River Area:

Water quality issues

Water quality testing found toxic chemicals in the water of the Yakima River and some of its tributaries. Most of these chemicals are banned pesticides or PCBs (polychlorinated biphenyls) that are no longer used.

Past studies show that some of these chemicals get into the water when contaminated soil erodes and enters the water. Some of these chemicals were also found in fish living in the Yakima River and some of its tributaries.

The upper Yakima River is also on the 303(d) list for water temperature. Monitoring done near Cle Elum and near the Wenatchee National Forest revealed water temperatures that did not meet state water quality standards. (See study map.)

Upper Yakima River photo, Washington State. Photo courtesy of Jane Creech, Department of Ecology.

Status of the project

Suspended sediment and turbidity

Current and upcoming status

Ecology is developing a reserve loading capacity for the Upper Yakima Suspended Sediment, Turbidity and Organochlorine Pesticide Total Maximum Daily Load (TMDL).

The reserve capacity will be 10 tons per day of suspended sediment, and is allowed by reclaiming some of the unused loading capacity assigned to the TMDL’s load allocations. A small portion of this reserve capacity will be used to set a new wasteload allocation for the proposed Melvin R. Sampson coho salmon hatchery. The reserve capacity may also be applied to additional future permitted discharges.

In 2018, Ecology will assess full compliance for this TMDL.

Note: all requirements of the TMDL implementation plan remain in effect after compliance has been achieved.


Previous timeline

2011 The TMDL compliance period was extended with the understanding that Ecology would assess TMDL compliance in 2016.
2006 - 07 Ecology and several local partners completed a first round of effectiveness monitoring. The monitoring results showed that TMDL implementation was successful so far. Local activities to reduce suspended sediment activities resulted in lower total suspended sediment (TSS) and turbidity values in 2006, compared to 1999.
2003 Ecology and local entities developed a more detailed implementation plan which laid out the actions needed to address the pollution issues and achieve target loads prescribed in the TMDL.
2002 The TMDL was approved by EPA.
2000-2001 Ecology, along with local interest groups, developed a total maximum daily load (TMDL) report. The report contained a summary of the results of water quality studies in the upper Yakima watershed, and an implementation strategy that discussed the goals, objectives, and strategies to implement cleanup recommendations in the study.



Ecology and its local partners collected extensive water temperature data in tributaries of the upper Yakima River. Ecology scientists used this data to model the many factors that affect stream temperature .In general, the scientists found that the effective shade produced by full potential streamside vegetation is needed to meet water quality standards for temperature in the upper Yakima tributaries. They developed a draft water quality improvement report and implementation plan to reduce water temperatures in certain portions of upper Yakima tributaries. This report and plan was approved by EPA in 2016. Stakeholders have already initiated many actions to reduce stream temperatures in the project area.


Farmers and other land users in the watershed implemented existing TMDLs that may help 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. Monitoring of DDT, dieldrin, and other chlorinated pesticides continues to measure the progress of other water quality improvement project work to bring the watershed into compliance with state water quality standards.

Ecology conducted a study on water quality conditions in the Yakima River watershed in 2006. Although additional sources of toxic contamination to the surface waters were found, 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 their advisory on DDT in lower Yakima River fish.

Why this matters

Suspended solids impair fish and aquatic insect respiration. Particles can also settle and clog spawning gravel or suffocate fish eggs. Suspended sediments can also carry organochlorine pesticides into the water.

The Department of Ecology (Ecology) believes the control of suspended sediment generation and transport during the irrigation season will result in far-reaching water quality and fish habitat improvements in the Yakima Basin.

Water temperature influences what types of organisms can live in a water body. Cooler water can hold more dissolved oxygen that fish and other aquatic life need to breathe. Warmer water holds less dissolved oxygen. Many fish need cold, clean water to survive.

One way to cool water temperature is to shade the water body by adding or retaining streamside vegetation.

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.

Turbidity reduces the amount of light penetration in the water, and can interfere with natural productivity in the river. Turbidity also makes it more difficult for fish to move, avoid predators and find food.

Technical information

Unless otherwise specified, the following document are Ecology publications.

Suspended sediment and turbidity

Data Summary: Upper Yakima River Basin Suspended Sediment and Organochlorine Pesticide TMDL Evaluation

Upper Yakima River Basin Suspended Sediment and Organochlorine Pesticide Total Maximum Daily Load Evaluation

Upper Yakima River Basin Suspended Sediment, Turbidity and Organochlorine Pesticide TMDL Submittal Report

Upper Yakima River Basin Suspended Sediment, Turbidity and Organochlorine Pesticide TMDL – Detailed Implementation Plan

  • Addendum added 01/31/2013

Quality Assurance Project Plan: Suspended Sediment and Turbidity Total Maximum Daily Load Effectiveness-Monitoring Project in the Upper Yakima River Basin April to October 2006

Yakima River Basin Suspended Sediment, Turbidity and Organochlorine Pesticide Total Maximum Daily Load Study: Water Quality Effectiveness Monitoring Report

Project Update for the Upper Yakima River Basin Suspended Sediment, Turbidity, and Organochlorine Pesticide Total Maximum Daily Load (TMDL)

Quality Assurance Project Plan: Status Monitoring for Upper Yakima River Suspended Sediments and Organochlorine Pesticides


Quality Assurance Project Plan: Upper Yakima Basin Temperature Total Maximum Daily Load Study

Upper Yakima River Tributaries Temperature Total Maximum Daily Load: Water Quality Improvement Report and Implementation Plan


Concentrations of 303(d) Listed Metals in the Upper Yakima River

Verifying 303(d) DDT/DDE and Dieldrin Listings for the Upper Yakima River

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

Chlorinated Pesticides, PCBs, and Dioxins in Yakima River Fish in 2006: Data Summary and Comparison to Human Health Criteria

Quality Assurance Project Plan- Yakima River Chlorinated Pesticides, PCBs, Suspended Sediment, and Turbidity Total Maximum Daily Load Study

Upper Yakima River Suspended Sediment Total Maximum Daily Load Quality Assurance Project Plan

Yakima River Pesticides and PCBs Total Maximum Daily Load: Volume 1: Water Quality Study Findings

Upper Yakima River Watershed DDT and Dieldrin Monitoring, 2014: Status Monitoring for TMDL

Related information

Unless otherwise specified, the following document are Ecology publications.

Suspended sediment and turbidity

Focus on Upper Yakima Basin - Restoration plan targets sediment


Focus on Water Temperature in the Upper Yakima River Basin

Wenatchee National Forest Water Temperature Total Maximum Daily Load: Technical Report


New information available on toxic chemicals in Yakima River (Ecology news release)

Yakima River Watershed Toxics Study

Frequently Asked Questions: Yakima River Watershed Toxics Study: Progress Update

Fish Consumption Advisories for Yakima River (WA Department of Health)

Flow Summary of Ten Stream And Irrigation Ditches in the Upper Yakima River Basin

WRIA 39: Upper Yakima Watershed Information (Water web site)


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November 2017
  Water resource inventory area (WRIA) 39 map, Washington State.


WRIA: #39 (Upper Yakima)


Water-body Name:
Yakima River

Suspended sediment

# of TMDLs:
Suspended sediment, turbidity, toxics - 19

Temperature - Approved by EPA; has implementation plan
Suspended sediment, turbidity, toxics - Approved by EPA; has implementation plan

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