A view of Lock and Dam 1 on the Mississippi River from an observation area on Friday during an open house in Minneapolis. (Aaron Lavinsky, Star Tribune/The Minnesota Star Tribune)

Two Mississippi River locks and dams in the heart of the Twin Cities are the subject of a federal study to discern whether they might be closed, sold — or even removed entirely.

The U.S. Army Corps of Engineers kicked off its research this month into the Lower St. Anthony Falls Lock and Dam, in addition to Lock and Dam No. 1, also known as the Ford Dam, because the hydroelectric power generated there formerly powered the Ford plant in St. Paul.

The study will examine whether the Corps still has an interest in operating the structures, which see little commercial traffic after the closure of the Upper St. Anthony Falls Lock and Dam in 2015. In a similar study, the Corps decided to relinquish ownership at Upper St. Anthony, and a campaign is underway to redevelop the site to highlight Indigenous history and ecological restoration.

The dam at Upper St. Anthony has to stay in place in part to stop the spread of invasive carp and maintain water levels for Minneapolis' drinking water intake upstream. But the Corps is required by Congress to study the possibility of removing the next two locks and dams downstream.

"It's kind of an exciting study, [to look at] these big structures in such an important area, in the heart of an urban area," said Clay Tallman, a Corps project manager.

In addition to removal, the Corps could conclude that another state or federal agency should take over the locks and dams, or it could decide to sell them to a private entity.

Removal would be extremely rare for the highly controlled Mississippi, where locks and dams essentially create an elevator for watercraft. Olivia Dorothy, upper Mississippi River director for advocacy group American Rivers, said the only other dam removal in recent memory was near St. Louis, at Lock and Dam 26. It was demolished in 1990 after significant structural issues, and replaced.

As a part of its study in the cities, the Corps is holding public meetings and accepting comments until Nov. 25.

As she attended an open house at Lock and Dam 1 on Friday, Nancy Ford, owner of used outdoor goods store Repair Lair in Minneapolis, said this section of the Mississippi was "underutilized and underappreciated."

Ford said she had visited and paddled on the stretch for most of her life. She worried that removing the structures could release the silt built up behind them over the years. She said if they closed and stayed in place, it would create a long portage for paddlers.

"If you tear it out, is it going to be more accessible? Less accessible? I don't know," she said.

All the dirt that has built up for a century behind the dams, and any toxic substances it may hold, is one of the reasons some environmental groups are stopping short of endorsing removal. But the National Parks Conservation Association recently commissioned renderings of what the river might look like if the locks and dams were torn out.

Christine Goepfert, associate director with the NPCA, said the images show the ways that removal could shape the cities' relationship with the river. Rapids might emerge and allow for uses like tubing, and increased shoreline might help more people get to the river for fishing.

A view of what the Mississippi River might look like at Lower St. Anthony Falls, if the lock and dam there were removed. (Rendering courtesy of the National Parks Conservation Association./The Minnesota Star Tribune)

Though there might be harms lurking in built-up sediment, there are significant environmental benefits to removal, said Colleen O'Connor Toberman of Friends of the Mississippi River. The group is also not formally endorsing removal of the locks and dams.

The dams create elongated lakes in the waterway, rather than a free-flowing river with a natural slope, thus significantly changing the ecosystem, O'Connor Toberman said. Mussels and some fish might benefit from dam removal.

"We've only been damming it and trying to control it this way for under 200 years," she said. "What we accept as the only way the river is, the only way that river can be, is actually just a blip in history."

Removing the structures would eliminate the staircase effect of the dams, and cause water levels in some sections to drop. That could lead to an extension of the banks around the river and potentially new islands — which also creates a question of who would own and manage that land, Goepfert said.

Dorothy said that effects on the bridges and other infrastructure around the dams need to be studied too.

Her group, American Rivers, advocates for dam removals around the country to help wildlife habitat, but she said, "Sometimes it's just not feasible, there are complications."

Both dams are also still generating enough hydroelectricity for a combined 12,100 homes per year, said Nanette Bischoff, a retiring project manager with the Corps.

The final decision from the Corps will be years in the making. Tallman, the project manager, said that a draft of the study will be available for another round of public comment late in 2024, and a final study and recommendation will be sent to Congress in mid-2025.

"For the first time since the Twin Cities were established, we have a chance to redefine what the river in the heart of the Twin Cities means to us," said John Anfinson, former Corps historian and former superintendent of the Mississippi National River and Recreation Area.

The Corps is accepting public comments now on what issues it should consider as it begins the investigation. The public can submit comments via email to MplsLocksDisposition@usace.army.mil, or attend a public meeting at Dowling Elementary School in Minneapolis from 6 p.m. to 8 p.m. on Oct. 25. More information is available at mvp.usace.army.mil/MplsLocksDisposition.