This summer, when hordes of visitors stop to admire the torrent of water that flows over the falls at the St. Anthony Lock and Dam in Minneapolis, they will be standing at a turning point in the 100-year relationship between the Mississippi River and the cities founded along its banks.

The lock closed two years ago, and now the Army Corps of Engineers, the federal agency that controls navigable waters nationally, is undertaking a major review of what it will do with it and two others just downstream.

The review could take years to complete, but already a long line of powerful government and advocacy groups are lining up for what promises to be a historic and perhaps acrimonious civic debate rooted in one simple question: What kind of Mississippi River do Twin Citians want for the next century?

“We are living with the vision of the people from the past,” said John Anfinson, superintendent of the Mississippi National River Recreational Area for the National Park Service. “But for first time in 100 years, we have a chance to think about the river’s 21st century relationship with the Twin Cities.”

Several competing, and sometimes extraordinary, visions have already emerged. One plan would completely remove two dams and restore the natural wild flow and rapids of the Mississippi gorge. Another would create a world-class National Park visitors’ center at St. Anthony Falls. Or things could remain just as they are for placid waters, flood control and hydroelectricity.

The Upper and Lower St. Anthony locks were closed to protect Minnesota’s northern lakes and rivers from the spread of Asian carp. By order of Congress, the massive lock gates have been bolted shut and the lifts removed. This summer, the lock will be open for tours conducted by the National Park Service.

Now it’s time for the Corps to decide, by mid-July, whether it still has a navigation role to play along the urban stretch of the river above its confluence with the Minnesota River at Fort Snelling, said Nan Bischoff, the Corps’ project manager for the lock and dams disposition study.

Flood control, energy

Right now, the St. Anthony and Ford Dams generate hydropower for Xcel Energy. The Upper St. Anthony lock can help control upriver flooding by opening the gates at the top of the lock, and the lock at the Ford Dam still moves fishing boats, cruise boats and the occasional barge up the river.

“Is that enough to fulfill our mission?” Bischoff said, since altogether they cost the federal government about $1.5 million a year to operate. If the decision is no, then the Corps will launch a longer-term review for all three structures.

While the Corps has closed or let go of major facilities before, it’s never confronted something quite as big and complex as this, she said.

“It’s unique in that it’s right in middle of a metropolitan area and there are so many eyes on it,” she said.

By law, the Corps has to determine the “best and highest use,” she said.

That’s where the debate has already begun.

For starters, a national environmental group called American Rivers may propose what would be a highly controversial idea: Removing the Lower St. Anthony and Ford dams altogether, restoring the river’s natural wild ride through a gorge that drops 110 feet to the Minnesota River. Boulders now hidden in deep water created by the dams would instead generate breathtaking rapids in the spring that would attract white-water kayakers from around the world, said Olivia Dorothy, associate director for American Rivers, which works on dam removals across the country. And it would bring back many species of native fish, like river sturgeon, that once made their way up to the falls.

“This would be … a national river restoration success story,” she said.

During low water, Anfinson said, people could use the river for inner-tube floating, like a massive Apple River, or even boulder-hopping from one shore to the other.

But the Ford Dam still provides hydropower, and the smooth flat surface above it is ideal for the University of Minnesota and other rowing clubs. It’s also a growing area for anglers and boating.

“It’s not like recreation will go away, but it would change,” said Dorothy.

American Rivers will host its first community meeting to present its proposal in Minneapolis on July 13. “It has to be something the community wants,” Dorothy said. “But we can bring the tools and expertise to make it happen.”

Another group, the Friends of the Lock and Dam, has proposed making the St. Anthony lock a $45 million national visitors and interpretive center with restaurants, an event center and a glass-sided observation platform beside the falls.

Anfinson said it could double as a premier National Park visitors center for the Mississippi River that could easily outclass sites in Memphis and New Orleans.

“This is our chance to create a world-class destination,” he said.

It would lie in the heart of the Minneapolis Park and Recreation Board’s planned Water Works Park near the Stone Arch Bridge.

But it would conflict with a long-standing effort by Crown Hydro to generate electricity with newly installed turbines near the lock, which has drawn opposition from the Park Board and riverfront residents.

What’s critical now, Anfinson said, is that Minnesotans recognize they have a once in a generation chance to develop a new vision for the river:

“What I want is a really robust conversation so we can make a very intentional decision about what our future relationship with the river is.”