Cascade Water Alliance seeks permit for Washington hydroelectric project

The Cascade Water Alliance applied Feb. 3 to the Federal Energy Regulatory Commission for a preliminary permit for the proposed White River-Lake Tapps Reservoir Ancillary Hydroelectric Project in the state of Washington.

The project would utilize an existing reservoir, Lake Tapps, and other existing infrastructure associated with a former hydroelectric power facility owned and operated by the the alliance. The project would be located approximately 20 miles east-southeast of Tacoma in Pierce County, Washington. It would rely on water diversions from the White River.

Under the applicant’s current operations, water flows into Lake Tapps through an upper conveyance system consisting of 7.5 miles of flumes, canals, dikes, settling basins, and pipelines (called the “Upper Conveyance”). Water exits Lake Tapps by means of a lower conveyance system that includes a concrete-lined tunnel, steel penstocks, a hydroelectric powerhouse, and a free-flowing tailrace (collectively the “Lower Conveyance”), eventually returning to the White River at RM 3.6.

The existing facilities were built in 1911 and operated for hydroelectric power generation until January 2004. After power generation ceased in 2004, the prior owner of the facilities continued water diversion for recreational purposes on Lake Tapps. In December 2009, the alliance purchased Lake Tapps and related facilities as a source of municipal water supply. The applicant intends to use the existing infrastructure associated with Lake Tapps, including the Upper Conveyance and Lower Conveyance, after developing Lake Tapps into a source of municipal water supply. The proposed hydroelectric roject would be ancillary to the applicant’s present and future use of the Lake Tapps Facilities for municipal water supply purposes.

  • In the Lower Conveyance, the applicant would utilize the existing powerhouse by returning the existing turbine, generator, and transmission facilities to service, providing the potential for up to 27 MW of generating capacity via one of the four existing penstocks. In a second penstock, an in-line turbine generator on the order of 5 MW would be installed capable of operating over a range of lower discharge volumes. This second generator could be operated in parallel with or in lieu of the existing generator. Discharges from Lake Tapps would be conveyed through these generators as a means of energy dissipation and power recovery.
  • Along the Upper Conveyance, the applicant would install an in-line turbine generator with a capacity of roughly 5 MW at an existing valve house located on one of two parallel tunnels. River diversions into Lake Tapps conveyed through this Upper Conveyance generator would discharge energy by recovering power.

Contact information is: Cascade Water Alliance, 520 112th Ave NE, Suite 400, Bellevue, WA 98004, Main phone: (425) 453-0930, Fax: (425) 453-0953, Chuck Clarke, Chief Executive Officer,

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.