Water Quality Improvement Projects
Walla Walla Watershed:


The Walla Walla watershed is located in southeastern Washington State in Walla Walla and Columbia counties, extending into Oregon. This drainage basin covers approximately 1760 square miles, two-thirds of which are within Washington. The Walla Walla River starts in Oregon, flows north into Walla Walla County, and drains into the Columbia River. Major tributaries to the Walla Walla River include the Touchet River, Dry Creek, Pine Creek, and Mill Creek. (See study area maps)

Water quality issues

As early as 1998, the Washington Department of Ecology (Ecology) discovered the water quality data for some streams and rivers in the watershed did not meet the state's water quality standards. As a result, these streams and rivers were placed on the 303(d) list. In 2004, Ecology included additional watershed streams on the list. The streams have low dissolved oxygen, too many chlorinated pesticides and PCBs, high temperatures, fecal coliform bacteria, and pH levels.

Walla Walla River, Washington State.  Photo courtesy of Karin Baldwin, WA Department of Ecology.

Why this matters

These pollutants impact everyone. Chlorinated pesticides and PCBs can make fish unhealthy to eat and can build up in our bodies and lead to health problems. High levels of bacteria can make us sick. Temperature, pH and dissolved oxygen can create a difficult or impossible environment for fish to live in, which can reduce recreational fishing opportunities and further harm endangered or threatened fish.

What was done

Ecology began a water quality improvement project (also known as a Total Maximum Daily Load or TMDL) in the watershed to bring watershed streams and rivers into compliance with state water quality standards. Due to the size and complexity of the Walla Walla watershed, Ecology developed four different TMDLs in the watershed:

  • Chlorinated pesticides and PCBs: Chlorinated pesticides and PCBs are chemicals that are recognized as known or possible human carcinogens. Although these chemicals were banned in the U.S. in the 1970s and 1980s, they are often called “legacy pollutants” because they persist in the environment for many years.
  • Fecal coliform bacteria: these bacteria are found in the feces of warm-blooded animals. When found in bodies of water, fecal coliform can indicate the presence of other disease-carrying organisms called pathogens. People swimming or playing in water can be exposed to pathogens when they enter the body through small cuts, abrasions, mucus membranes, or accidentally swallow water.
  • Temperature: When water temperatures are too high, streams can become uninhabitable for fish and other aquatic animals. Many salmon and trout species may suffer decreased spawning success and even death when waters are too warm. In addition, the warmer the water, the less dissolved oxygen it can hold.
  • Dissolved oxygen and pH: Dissolved oxygen (DO) is necessary for fish and plants to breathe. DO is needed to help decompose organic matter in the water and bottom sediments. It is also necessary for other biological and chemical processes. pH is a measure of how acidic or basic the water is. pH affects the chemistry and chemical reactions that take place in the water, such as the solubility of nutrients and metal compounds.

Status of the projects

The Environmental Protection Agency (EPA) approved all four TMDLs by August 2007. In addition to working on these TMDLs, Ecology and the Walla Walla Watershed Planning Unit's Water Quality Subcommittee continued their partnership to write a water quality implementation plan. The implementation plan guides the work that is planned to improve water quality. The plan was completed in December, 2008. Over fourteen organizations committed to help improve water quality by educating the public, restoring native trees and shrubs along streams, reducing pollution in stormwater, and installing off-stream water troughs and fences to control livestock. The Water Quality Subcommittee prioritized streams in the watershed where work to improve water quality should begin. Ecology staff are currently providing technical assistance and working with organizations in these prioritized areas.

As of January 2014, the people in the Walla Walla Watershed installed over 4,200 acres of riparian restoration projects along 224 miles of streams on agricultural lands through the Conservation Reserve Enhancement Program (CREP). They also implemented 80 riparian restoration projects along over five miles of streams in the Walla Walla and College Place urban growth areas. Riparian buffers provide shade to cool streams, reduce erosion of streambanks, filter pollutants from stormwater, and provide important habitat for many species of fish and wildlife.

Farmers have enrolled over 193,000 acres of cropland in the Conservation Reserve Program (CRP). This program reduces soil erosion by planting highly erodible cropland with perennial vegetation. The city of Walla Walla and Walla Walla County have active programs to reduce water pollution caused by stormwater runoff. Several groups are working on shallow aquifer recharge projects. These projects divert spring runoff water to areas with highly permeable soil to allow the water to infiltrate into the shallow gravel aquifer. The shallow gravel aquifer is in hydraulic continuity with the Walla Walla River and other streams, meaning the aquifer and the streams exchange water. Increasing water volume in the shallow gravel aquifer could improve flows in streams during the summer months. Increased flows can improve water quality and habitat conditions for fish, including threatened bull trout and steelhead, and reintroduced spring Chinook that call the Walla Walla Watershed home.

Beginning in the summer of 2014, staff from Ecology’s Environmental Assessment Program is conducting a water quality monitoring project to see if the work implemented has improved water quality conditions. They will conduct monthly monitoring through mid-2015.

Technical information

The following documents contain more information about the water quality problems found in the watershed and the activities that will be used to improve water quality (Note: unless otherwise specified, the following documents are Ecology publications)

Walla Walla Watershed PCBs, Chlorinated Pesticides, Fecal Coliform, Temperature, pH & Dissolved Oxygen Total Maximum Daily Load: Water Quality Implementation Plan.

Chlorinated Pesticides and PCBs:


Fecal Coliform Bacteria:

Dissolved Oxygen and pH:

Related information

Walla Walla River Basin Fecal Coliform Bacteria, pH, and Dissolved Oxygen Total Maximum Daily Load: Supplemental Study

In January 2006 the Washington State Department of Health issued a fish consumption advisory for Northern Pikeminnow and Carp in the Walla Walla watershed. More information about this fish advisory is available on the Washington State Department of Health website.

In 2000 and 2002 Oregon DEQ analyzed the entire length of the Walla Walla River. Ecology used Oregon DEQ’s assessment to develop a temperature TMDL for the Walla Walla River in Washington. For information about that analysis please visit Oregon DEQ’s Walla Walla website.

During the summer of 2002, Watershed Science LLC of Corvallis, Oregon used helicopters mounted with thermal infrared radiometry (TIR) equipment to take a “picture” of the heat radiating from the water. This data provides an overall picture of the watershed temperature conditions. To learn more about the helicopter survey, please see Water Cleanup Plans: Taking the Temperature of the Walla Walla Watershed.

WRIA 32 Watershed Planning

Walla Walla County Conservation District

WRIA 32: Walla Walla Watershed Information (Water web site)


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Last updated September 2014
  Water resource inventory area (WRIA) 32 map, Washington State.


WRIA: #32 (Walla Walla)
Walla Walla

Water-body Name:
Walla Walla River and Tributaries

Chlorinated Pesticides and PCBs
Fecal Coliform
pH and Dissolved Oxygen

# of TMDLs: 54 total

All four TMDL reports approved by EPA.
Has an implementation plan for all parameters

Contact Info:
Mike Kuttel
Phone: 509-329-3414
Email: Mike.Kuttel@ecy.wa.gov

Eastern Region
Department of Ecology
4601 N. Monroe
Spokane, WA 99205