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For additional information about this project, visit Ecology’s website.

Lake Tapps Regional Water Rights Support

Client: Puget Sound Energy (PSE) Location: King & Pierce Counties, WA Contact us for more information.

Project Background & Challenges

PSE has operated the Lake Tapps reservoir as a long-time hydropower source. When the hydropower project became financially unsustainable, PSE sought another revenue source to maintain the lake. Consequently, the utility decided to apply for both a new water right and a change in its existing rights. The objective was to allow water that was historically diverted for hydropower to be used for other purposes, including a new regional supply operated by the Cascade Water Alliance. PSE's proposed change has engaged a broad spectrum of stakeholders: Native American tribes, lakeside homeowners, and downstream utility providers, as well as local, state, and federal agencies. Opinions differed widely on how best to balance these competing demands of maintaining instream flows, lake levels, and water quality.

Solution

Aspect assisted Ecology and the Attorney General's Office in processing the water right application. Over our nine years of project involvement, we performed statistical analysis of streamflow records and evaluated the effects of implementing alternative targets for minimum instream flows and seasonal lake levels. We have also characterized the complex operations of the diversion, storage, and release facilities and coordinated with a diverse group of basin stakeholders. In fall 2010, Ecology approved the water rights application, complimenting Aspect’s contributions to the high-profile project.