Brett French | bfrench@billingsgazette.com
Smallmouth and largemouth bass have been illegally introduced into a Livingston pond that’s connected to the Yellowstone River and its prized trout fishery.
To remove any chance the fish may migrate from Sacajawea Lagoon into the stream, Montana Fish, Wildlife & Parks staff is proposing to remove the fish. A public meeting on Thursday, Oct. 1, will provide the public a chance to hear about the project. The meeting will be held at 5 p.m. in the Community Room of the City/County Complex building at 414 E. Callender Street in Livingston.
The presence of bass so close to the Yellowstone River is a serious concern.
In 2020, a smallmouth bass was caught in the Shields River, downstream from a reservoir where the fish were detected.
In 2022, an angler caught a smallmouth bass near the mouth of the Gardner River, a tributary to the Yellowstone about 50 miles upstream from Livingston.
The discovery prompted FWP to enact a catch-and-kill regulation for bass in the upper river as Yellowstone National Park officials feared the fish may migrate into the park, homeland of the namesake Yellowstone cutthroat trout where the park has spent millions of dollars and years of efforts to protect the fish.
FWP received reports of smallmouth bass in the Sacajawea Lagoon in late May, according to the agency. Six largemouth bass and three smallmouth bass were captured using electrofishing by FWP staff on June 1. The largemouth bass ranged from 11-12 inches, while smallmouth bass ranged from 10-13 inches.
“Escapement of bass from the lagoon is possible through a culvert near the inlet of the lagoon that is directly connected to the Yellowstone River,” FWP wrote. “Downstream dispersal of bass into Fleshman Creek, which is connected to the Yellowstone River, is also possible through the outlet structure.”
Smallmouth bass have been reported in the Yellowstone River by anglers near Livingston and are found in high abundances downstream of Billings, FWP noted. However, smallmouth bass reproduction is thought to be limited near Livingston, which has restricted their abundance and distribution in the upper Yellowstone River.
FWP is proposing to remove all fish from the lagoon by periodically capturing fish while electrofishing as the lagoon is dewatered. To dewater the lagoon, a diversion barrier will be placed where Fleshman Creek enters the lagoon to divert water to the Yellowstone River. The lagoon outlet will be screened to minimize fish escapement downstream.
Once screens are in place, check boards on the outlet will be incrementally removed over several days to gradually drain the lagoon to avoid bank erosion and other issues that might result from high flows in Fleshman Creek in residential areas downstream of the lagoon, FWP wrote.
The work will dewater about a mile of Fleshman Creek downstream of the lagoon. However, a spring near M Street should maintain low flows in Fleshman Creek to its confluence with the Yellowstone River.
FWP staff will capture and relocate as many fish as possible from the dewatered section of the stream to the section of stream below the spring. The dewatered reach of Fleshman Creek downstream of the lagoon would remain dewatered until the lagoon is full. All fish will be collected once the lagoon is completely dry. Captured fish will be euthanized and removed from the lagoon. Yellowstone cutthroat trout will be stocked following removal efforts.
The work should be completed between Dec. 11 and June 30, 2027.
The meeting scheduled in Livingston will provide an opportunity for the public to learn more about the proposed project and ask questions of FWP staff. FWP will also provide information on long-term management plans for the Sacajawea Lagoon fishery.
Public comment on the draft environmental assessment for the project is open until Oct. 2. For more information on the project, including commenting details, visit https://fwp.mt.gov/public-notices/news/2026/sep/sacajawea-lagoon-largemouth-and-smallmouth-bass-removal-fwp-cea-fsh-r3-26-031.
Editor’s note: Corrected an invalid completion date from 'June 31, 2027' to 'June 30, 2027' (June has only 30 days).
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