PPL Montana biologist lures fish to Thompson Falls ladder
Brent Mabbott plays critical role in helping the company protect, preserve and enhance the environment
When I recently encountered a 28-pound northern pike and a 4-pound largemouth bass in the Thompson Falls Reservoir, it reminded me what a dynamic fisheries resource we have in Montana.
Working for the past five years on PPL Montana’s fish ladder at Thompson Falls Dam, which will be formally dedicated on Sept. 8, I’ve had a front-row view of this very interesting fishery. We have non-natives such as walleye and northern pike and the native populations of bull trout and westslope cutthroat trout. It’s a diverse fish population and a sure sign that our rivers and watersheds are clean, something in which we should all take a measure of pride.
As the senior fisheries biologist for PPL Montana, it’s my job to work with state, federal and public agencies to make sure PPL Montana is protecting, preserving and enhancing our state’s fisheries habitat.
The fish ladder at our hydroelectric plant at Thompson Falls is one of the important measures we’ve taken.
The ladder — which replaces an experimental, small-scale temporary fish passage system used since 2003 — has 48 individual concrete step pools that will permit fish to gradually ascend about 75 feet to the top of, and over, the dam. The fish ladder will reopen hundreds of miles of the upstream Clark Fork River and its tributaries for native bull trout, westslope cutthroat trout and other fish species.
We conducted nearly five years of research to determine the best site for the ladder. Using radio tracking of fish, we worked with other biologists, hydrologists and engineers to determine river flow patterns and where fish, in their upstream migration, would most likely approach the dam.
The ladder’s design is targeted for bull trout, which are bottom dwellers, but almost all species will be able to use it. This is the first ladder in the continental United States specifically designed for bull trout. It’s a true innovation. Because so little is known about bull trout using a fish ladder, we have designed a ladder that allows for either bottom or surface ascension through the pools. Antennae at the top and bottom of the ladder will measure how long it takes marked fish to go up and over the dam.
We will also work with the state of Montana to radio tag and monitor selected fish species that we allow to go over the dam.
Analyzing the genetic code of the bull trout in the Clark Fork River is another big part of what we do. We work closely with Montana Fish, Wildlife and Parks and the U.S. Fish and Wildlife Service on this genetic mapping to help us understand where the fish came from and what natal streams they are headed back to spawn.
From every perspective, Thompson Falls is a great place to observe wildlife and savor the outdoors.
The recently reopened High Bridge, on the south side of Island Park in Thompson Falls, allows new pedestrian access to trails and other recreation sites owned and maintained by PPL Montana. PPL Montana provided cost-share funding and active support for the bridge project. It also leads to the observation deck overlooking the new fish ladder.
The fishing is great here. The diversity is amazing. Northern pike that are more than 30 pounds, with largemouth and smallmouth bass and trout, too. I enjoy observing the small game, deer, turkey, mountain goat, elk and bear. Fishing osprey chatter at you all the time.
The whole world explodes with life here. It’s exciting.
I can’t think of a better job.
Access: PPL Montana’s Thompson Falls hydroelectric plant offers recreation opportunities to residents and visitors of the city of Thompson Falls. Near the access road to the powerhouses, PPL Montana owns and maintains Power Company Park. The park’s facilities include an accessible sheltered picnic area, tables, benches and restrooms. The parking lot is also used for visitors who recreate downstream of the original powerhouse.
PPL Montana also owns and maintains the Thompson Falls Island public day-use area, which is in the middle of the river and separates the “Main Dam” and “Dry Channel Dam.” Facilities on the island include accessible trails, overlooks, picnic tables, toilets and interpretive signs. Pedestrians and bicyclists can access the island from Thompson Falls across the Gallatin Street Bridge and the recently reopened High Bridge between the island and the south side of the river.