Posted on October 19, 2026
Next Tuesday, Livingston city commissioners are scheduled to discuss the prospect of dredging the Sacajawea Lagoon.
City staff are asking city commissioners to consider whether to take advantage of an opportunity afforded to them by the Montana Department of Fish, Wildlife, and Parks (FWP).
FWP plans to dewater the lagoon to remove non-native fish species this winter. With that state agency taking point on the issue, that would alleviate some of the burden on the city if the latter opted to dredge the lagoon. In spring 2025, City Manager Grant Gager told The Enterprise that dredging the lagoon would be quite an undertaking for the city.
“The city would have to maintain a bypass pumping operation to take water entering the lagoon and then deposit it into Fleshman Creek downstream of the pool and the weir there,” Gager said in March 2025. “I don’t think that the DEQ would allow us to dewater the lower part of Fleshman Creek and kill all of the wildlife down there that depends on it.”
Such an effort would require permits from the U.S. Army Corps of Engineers, he added.
“It actually is likely to be a very large undertaking when it happens,” Gager said. “It’s something that the city recognizes needs to be addressed, but it is one of many priorities.”
Last month, FWP announced it wants to remove invasive bass from the lagoon. The project would involve a diversion barrier 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,” reads the FWP project description. “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.”
The project, if approved by the state wildlife commission, also would dewater about a mile of Fleshman Creek downstream of the lagoon.
“With the State’s likely dewatering of the lagoon, the City of Livingston is presented with an opportunity to work on lagoon restoration,” reads a city staff report that will be presented to the city commission on Tuesday. “Dredging the lagoon to remove accumulated sediment would help to improve water quality and flow. Staff welcomes the Commission’s direction on the City’s participation with FWP in projects to enhance the lagoon’s water quality and flows. The City Commission has previously allocated $100,000 for lagoon restoration. Additional funds may be available from FWP’s Community Pond Grants Program.”
Silt in the lagoon has increased since it was last dredged more than four decades ago. The entire lagoon was around 18 inches deep on average until it was dredged in late 1980 by the Save Our Lagoon Foundation with funding from various state agencies, according to a 2021 report to the commission by Floating Island International. In 1980, the lagoon also was engineered to reduce the entry of silt by blocking water from Fleshman Creek in favor of Yellowstone River water. But nature had other plans: the Yellowstone’s channel changed, halting the flow of river water into the lagoon. The only source of water for the lagoon reverted back to Fleshman Creek, according to the report.
Six years ago, Floating Island International advised the city to use a BioSwale system to intercept and remove total suspended solids (TSS) in Fleshman Creek to prevent the TSS from accumulating in the lagoon.
“Since more than 98 percent of this accretion is inorganic, there is no practical ability to bio-digest it,” reads the report. “We conclude that The Sac [Sacajawea Lagoon] has sufficient existing surface area and circulation to biologically cycle most of the lagoon’s inflow nutrients out of the sludge already, but the sludge inorganics need to be dealt with.”
The sludge samples suggested that draining and dredging the lagoon would soon be necessary, according to the report.
“A potential alternative to draining and dredging would be to dredge several sites adjacent to shore, within reach of the arm of an excavator,” reads the report.
Tuesday’s event will be a regular meeting of the Livingston City Commission and will begin at 5:30 p.m. Oct. 20 meeting at the City/County Complex, 414 E. Callender St.
