Nisqually River Project

Tacoma Power began generating clean, renewable hydroelectric energy from the Nisqually River in 1912. At that time, a diversion dam was used to direct water to a powerhouse. That changed in 1945 when it was replaced by two much larger concrete structures: Alder Dam and LaGrande Dam. Today, these two dams generate enough energy to serve about 43,000 homes, making it our second-largest hydroelectric resource. Alder Lake is the 3,000-acre reservoir formed by Alder Dam.

Nisqually River Project map

Project Licensing

All four of our hydroelectric projects are licensed separately by the Federal Energy Regulatory Commission (FERC), which was created by the Federal Power Act to ensure safe and efficient operation of power plants across the U.S. Many other agencies, tribes, organizations and stakeholders are also an important part of the licensing process.

A second federal license for the Nisqually River Project was issued in 1997. It was developed with the Nisqually Indian Tribe, Nisqually River Council, the Washington Department of Fish and Wildlife, the U.S. Fish and Wildlife Service and the National Marine Fisheries Service.

Reservoirs and River Flow Control

Our federal license guides our priorities for managing the elevation of Alder Lake. The top priority is maintaining downstream river flows at or above a set minimum level. When natural river flow is less than the required minimum — mostly during summer and early fall — additional water must be taken from Alder Lake to achieve the minimum downstream flow. This helps improve habitat for salmon and steelhead. It is worth noting that our minimum flow is greater than what would naturally occur without the dams.

The next highest priority is keeping the lake’s elevation high during the prime recreation months. Alder Lake is considered a small reservoir and is unable to provide downstream flood control. Even so, we lower the elevation of the lake when possible during winter months to allow some capture of high water inflows from rain and snow melt.

We also enhance river flows by releasing water from LaGrande Dam to improve the habitat for Chinook and coho salmon spawning downstream of the dam.

Fish and Wildlife Programs and Public Recreation

Along with generating clean, renewable hydroelectric energy and maintaining water levels in our reservoirs, our FERC license includes mandates for:

  • Recreational access at Alder Lake Park, Rocky Point Campground and Sunny Beach Point for boating, water skiing, fishing, camping and day use.
  • kokanee fishery; we plant up to 500,000 fish in Alder Lake each year for anglers.
  • Funding for the Nisqually Tribe’s Clear Creek Hatchery, which produces about four million Chinook smolts and one million coho smolts each year.
  • Protection for 3,500 acres of land for wildlife in the Nisqually River basin.
Take a Tour

Free group tours of the Nisqually River Project facilities are available by appointment for school, civic, business and recreational groups during regular working hours. To make arrangements for a tour, please complete our request form.