A federal study that could lead to the removal of Mississippi River locks and dams in the Twin Cities was significantly underfunded this year, dimming the prospects of a free-flowing river anytime soon.

The Army Corps of Engineers started studying the Lower St. Anthony Falls Lock and Dam and Lock and Dam No. 1 last fall. This year, the Corps asked for $2 million to study several future scenarios — including keeping them in place, selling them or removing them entirely — but was awarded $500,000.

The Corps had planned to prepare a draft study for the public by the fall of 2024, but that timeline has been indefinitely delayed, according to Karla Sparks, a program manager for the St. Paul district of the Corps.

"It can be disappointing" not to get full funding, Sparks said. "We adjust and adapt."

Environmental groups had been closely watching the study — and the transformation it could bring to a roughly 6-mile stretch of the river as it winds through the heart of Minneapolis and St. Paul.

"We're going to see that study come out ... and we're just going to be like, 'Well, that doesn't answer anything for us,'" said Colleen O'Connor Toberman of Friends of the Mississippi River.

Taking out the dams would be an unprecedented project and one of the biggest structural removals ever on the Mississippi — only one other major dam, near St. Louis, was removed and later replaced.

The Twin Cities dams have been holding back roughly a century's worth of sediment, along with any pollution that may have settled in it. Ripping out the impoundments would lower water levels, potentially affecting infrastructure around the river and recreation on it.

Christine Goepfert, an associate director for the National Parks Conservation Association in Minneapolis, wrote in an email that the group is worried the Corps will under-examine "sedimentation, impacts on ecosystem, recreation and infrastructure from the various scenarios as well as economic analyses of the options."

Sparks said the Corps is still going to test what's in the sediment, and plans several trips with the National Park Service to track recreation, but acknowledged that there might be less of an economic analysis in the final report than environmental groups want.

Goepfert and O'Connor Toberman said they will start reaching out to researchers to see if they could do supplemental analyses. Sparks said that outside information might get incorporated into the final report.

The limited funding for this year is a symptom of the entire Corps budget for so-called "disposition" studies, Sparks said — and she said it's likely that many other similar studies outside of the St. Paul Corps district were also underfunded. It is possible the Corps could get additional money next year to help make up the gap in the study, she added.

Many people outside of environmental interest groups are also watching the study.

According to scoping documents released by the Corps in May, almost 300 members of the public wrote in with their own concerns. They asked what removing the dams would mean for the hydroelectric power supplied at each location, what the pitfalls of selling them to a private owner might be, how removing the dams would affect fishing and boating spots, whether native species might benefit from a freer waterway and whether invasive species might take advantage of it.

In the same documents, the Corps indicated that if it does ultimately recommend removing the dams, that would require an additional feasibility study — and even more congressional funding — to fully understand the environmental implications.