White River trust water donation completes
Lake Tapps Public Water Supply agreement

The Department of Ecology has signed an agreement with the Cascade Water Alliance (CWA) that will protect flows for fish in the White River until 2034 and beyond.

CWA is making a permanent donation of 684, 571 feet of water (equivalent to a football field covered with water 130 miles deep) to the state’s Trust Water Rights Program for the preservation of instream flows and to protect fish habitat in a stretch of the White River that flows through the Muckleshoot Tribal Reservation.

The largest in recent memory to the trust water program, the donation completes the agreement CWA made in 2010 to donate a portion of the water rights it acquired in the purchase of Lake Tapps from Puget Sound Energy.

CWA is the water purveyor for eight King County cities.  In addition to its permanent trust water donation, the alliance is donating another 154,751 acre feet of water (equivalent to an additional football field covered with water 29 miles deep) to the Temporary Trust water rights program until 2034.

The donated water stays in the White River for the benefit of fish, wildlife, recreation and the natural environment.  Ecology has agreed not to approve or issue new water right permits for 20.7 miles of the Reservation Reach of the river.

Water Supply Project Information

In 2010, Ecology issued to CWA four interrelated water rights and one water right change.  The water rights package completed a multi-year project to propose and develop a regional water supply system to meet the Central Puget Sound’s long-term municipal needs.  Lake Tapps is expected to provide a drinking water supply for nearly 400,000 residents in Bellevue, Redmond, Kirkland, Issaquah, Tukwila, the Covington Water District, the Sammamish Plateau Water and Sewer District and the Skyway Water and Sewer District.

CWA is also committed to preserving the lake for the benefit of surrounding homeowners, boaters, swimmers and anglers.

The water rights package approved by Ecology allows CWA to store water in the Lake Tapps Reservoir, divert water from the White River into Lake Tapps to supply water for the Water Supply Project, and withdraw water from Lake Tapps for municipal water supply purposes.  As currently proposed, the project will take 50 years to fully develop and gives CWA the authority to take an average of 48 million gallons of lake water a day (equivalent to a football field covered with water 147 feet deep) for public use.

In the News

Historical Background

Lake Tapps Reservoir, completed in 1911 by Puget Sound Energy (PSE) for hydroelectric power, is located in Pierce County. It is now owned and operated by the Cascade Water Alliance for eventual municipal water supply.  Currently, private residences and public and private parks surround most of the reservoir, with many boat launch facilities and docks. Lake Tapps Reservoir offers many recreational opportunities for both residents and the public, such as boating, water skiing, fishing and swimming.

PSE stopped hydropower operation in 2004 because of the costs of project operation associated with a Federal Energy Regulatory Commission hydropower license and sold the project to the Cascade Water Alliance in 2009.

The Cascade Project consists of a diversion dam on the White River at the town of Buckley, an 8-mile flow line, an off channel storage reservoir (Lake Tapps) and a powerhouse and tailrace canal that enters the White River below Auburn. Cascade, which has agreements with local tribes, cities and homeowners to ensure water for fish and people, is currently completing significant improvements to the entire system.

Under a vested surface water claim, water is diverted from the White River near the City of Buckley and conveyed to the reservoir through a flow line consisting of a series of channels and settling basins.  Approximately 20 cubic feet per second of the water is diverted from the flow line through a fish screen that prevents fish migrating downstream from entering Lake Tapps.

Water (and fish) diverted at the fish screen are returned to the White River several miles downstream of the diversion dam.

Trust Water Donation Document

Report of Examination - Ecology's decision documents

On September 15, 2010, Ecology approved and posted the final Lake Tapps Public Water Supply Project reports of exams.  The final water rights decisions and related appendices are posted below:

Comments Received on the Draft Reports of Examination

Draft decision reports were available for public review during a 45-day period between May 7 and June 30, 2010.  Ecology reviewed each comment and made some revisions to the reports of examination. The comments Ecology received are summarized in the following document:

Related Information Sources


White River Trust Water Donations
Lake Tapps Water Supply Project

Southwest Regional Office
Department of Ecology
PO Box 47775
Olympia WA  98504-7775
Phone 360-407-6859

Cascade Water Alliance
520 112th Ave. SE #400
Bellevue, WA  98004
Phone: 425-453-0930