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.

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.

What was done

Why this matters

Technical information

Related information


Last updated May 2016
  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:
David T. Knight
Phone: 509-329-3590
Email: David.T.Knight@ecy.wa.gov

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