Spokane River Upriver Dam and Donkey Island

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The Spokane River drains more than 4,900 square miles in Washington and Idaho. Industries and municipal wastewater treatment plants in the watershed upstream of the Upriver Dam and Donkey Island cleanup site have discharged polychlorinated biphenyls (PCBs) into the river. Two PCB deposits in river-bottom sediments were investigated and cleaned up from 2006 to 2007 under a consent decree Ecology entered into with Avista Development, Inc. (Avista) and Kaiser Aluminum & Chemical Corporation, the parties responsible for cleanup.

Cleanup was necessary because:

  • PCBs build up in the fatty tissues of humans, fish and animals and may cause harmful health effects. 
  • Removing or containing PCBs reduces contamination in the environment and provides a safer environment for children, adults, and wildlife using these areas.

The Spokane River Upriver Dam and Donkey Island site is divided into two cleanup projects. These areas are owned by the City of Spokane, the Washington Department of Natural Resources, and the Washington Department of Parks & Recreation. They are open to the public for recreational activities.

Placing the Cap Behind Upriver Dam
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Upriver Dam is located along Upriver Drive east of Greene Street in the City of Spokane. The project begins directly behind the dam and stretches east for nearly one-half mile, covering approximately 3.6 acres.

Known PCB sources to the dam area of the river include:

Under Ecology’s direction, contractors for Avista placed a three-layered cover called an engineered cap over the contaminated sediments on the river bottom. The cap is made of coal, sand, and gravel and is intended to isolate PCBs and keep contaminants from moving.

Dredging PCBs at Donkey Island
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The Donkey Island project is east of Upriver Dam in wetlands and backwater channels on the north bank of the river. The project is 0.25 acres in an unincorporated area. 

Ecology provided oversight as contractors removed PCB-contaminated soil and restored the area with clean sand.  Areas disturbed during PCB removal were replanted in spring 2007.


Ecology conducts a periodic review at least every five years after beginning cleanup at a site, as required by the Model Toxics Control Act (MTCA). The purposes of the review are to evaluate site conditions and to ensure continued protection of human health and the environment when environmental controls are used as part of a cleanup.

Ecology visited the site October 23, 2013, and found it is still owned by the State and is open to public recreation. Ecology used data from sediment samples taken in 2008 and 2010 to determine the remedies are still effective. 

The Periodic Review Report was available for public comment December 23, 2015, through January 27, 2016, and one question was received. Ecology answered the question in a response to comments document


Map showing site location as Spokane County, WA SITE INFORMATION


View Electronic Documents

Cleanup Site Details Report

Facility Site ID: # 65178472

Cleanup Site ID: 4213

Spokane, Spokane County

Status: Cleanup Complete-Active O&M/Monitoring   Get definitions of Status terminology

Brendan Dowling
Site Manager
(509) 329-3611

Erika Beresovoy
Public Involvement Coordinator
(509) 329-3546

Document Repositories:

Eastern Regional Office
N 4601 Monroe St
Spokane, 99205-1265