Cowlitz Fisheries Programs

Along with providing you with reliable electric service, restoring and maintaining quality fish habitat is one of Tacoma Power’s top priorities. It is also part of our license agreement with the Federal Energy Regulatory Commission, which oversees hydropower projects across the U.S.

We protect and promote fish habitat and migration in the following ways.

Fish Hatchery Management

We own and fund the Cowlitz Salmon Hatchery and Cowlitz Trout Hatchery. The hatcheries are operated by the Washington Department of Fish and Wildlife, while our employees sort the returning adult fish and complete all fish transportation to support migration, natural spawning, and harvest opportunities. We work to:

  • Provide a healthy environment for the early life stages of hatchery fish.
  • Help increase the number of adult fish that return to spawn.
  • Provide harvest opportunities for anglers to enjoy.
Trap-and-Haul for Fish Migration

The Mossyrock and Mayfield dams block natural fish passage on parts of the Cowlitz River. So to help coho salmon, Chinook salmon, steelhead and cutthroat trout complete their migration and spawning patterns, we use a trap-and-haul process. Here is how it works.

First, we collect upstream migrating adult fish at the Cowlitz Salmon Hatchery, which is downstream of Mayfield Dam, and sort them by species and destination. The fish are transported by truck to sites on the Tilton, Cowlitz and Cispus rivers to continue their spawning journey. Winter steelhead, fall Chinook, spring Chinook, coho and sea-run cutthroat trout are transported to upper basin release sites. Some of the fish remain at the hatchery to produce the next generation of salmon.

Juvenile salmon and steelhead migrating downstream from the upper Cowlitz River are collected by our Cowlitz Falls North Shore Collector, which runs through Lewis County Public Utility District’s Cowlitz Falls Dam, upstream of Riffe Lake. The fish are then transported by truck to stress relief ponds at the Cowlitz Salmon Hatchery. After acclimating in the ponds, the fish are released into the lower river to continue their journey to the ocean.

Diversion Screens and Fish Ladders

We use diversion screens to move downstream migrating salmon entering Mayfield Lake from the Tilton River into a fish passage channel at Mayfield Dam. This allows salmon to swim to the lower river without passing through the powerhouse turbines.

Upstream migrating salmon and steelhead in the Cowlitz River below the dams are diverted to a fish ladder at the Cowlitz Salmon Hatchery. From there, we transport them by truck to upper or lower river sites. Some of the adults are retained at the hatchery to produce the next generation of fish.

Fish Stocking

We stock Mayfield Lake, Swofford Pond, and South Lewis County Park Pond with rainbow trout to supplement existing fish populations and to provide recreational fishing opportunities. Fishing is also available at nearby Riffe Lake, which has most of the same species.

In addition, in 1988, the Washington Department of Fish and Wildlife (WDFW) began stocking tiger muskies in Mayfield Lake. This was done to provide a sport fish for anglers and to manage populations of northern pikeminnow, which are aggressive and a threat to native fish species.

Swofford Pond, a shallow, 240-acre artificial pond adjacent to Riffe Lake, contains rainbow, brown and cutthroat trout stocked by the WDFW, as well as resident largemouth bass, channel catfish and bluegill. Only electric motors are allowed on Swofford Pond, but there are many spots where you can fish from the bank.

Fish Habitat Fund

Our federal license for the Cowlitz River Project includes a $3 million fund to protect, restore and enhance fish habitat. This includes acquiring property and land easements as needed to complete our restoration efforts.

To oversee this work, a Habitat Advisory Group (HAG) was formed with representatives from:

  • Tacoma Power
  • Lewis County
  • U.S. Fish and Wildlife Service
  • American Rivers/Trout Unlimited
  • Washington Department of Fish and Wildlife

The group is responsible for approving the eligibility and setting priorities for property along the Cowlitz and Toutle rivers and their tributaries. The Fish Habitat Fund Allocation Plan provides a framework for evaluating and ranking the sites.

The Fish Habitat Fund may also be used as a source of matching funds for proposed project grants requiring multiple funding sources.

We encourage conservation groups and others to help us reach our restoration goals. To submit a proposal or idea to the HAG or to learn more about our program, contact us at

Ongoing Fish Restoration Efforts

Our Cowlitz River Project license calls for continual improvements to fish passage and survival. The Fisheries Technical Committee, which includes biologists from state and federal agencies, Tacoma Power, the Yakama Nation and a representative from Trout Unlimited and also American Rivers, directs the scientific studies needed to make decisions about the most effective fish-passage enhancements.