ROCHESTER - Major changes to a prominent lake face renewed scrutiny as some residents and neighbors say they're concerned the city is moving too fast to potentially remove a nearby dam, irrevocably changing the lake's shape.

They worry the Silver Lake Dam, first built in 1937, could lose its historic significance. They worry Silver Lake could revert back to being just another part of the Zumbro River. And they worry the city hasn't been forthcoming with more project details, including a grant proposal to fund the project using state dollars.

"Probably the main thing that concerns us is just a feeling that this grant proposal ... really was not very appropriate," said Greg Munson of the Friends of Silver Lake, a group that has long advocated for the lake and nearby park.

Lake supporters and critics plan to rally outside of city offices at the Olmsted County Government Center at 5 p.m. Monday, an hour before a Rochester City Council meeting. They hope Rochester will provide more answers on what could happen to Silver Lake.

City officials say they don't want to get rid of the dam, just tweak it. They plan to slightly shrink Silver Lake to about 85% of its size to improve water quality in the area. And the grant proposal made to the Lessard-Sams Outdoor Heritage Council last summer followed years of lobbying for other kinds of state funding.

Lessard-Sams "is specifically set up to complete habitat restoration projects and address impacts such as this," Deputy Public Works Director Aaron Luckstein said. "That funding source has actually been used for several other dam modifications throughout the state."

Silver Lake Park, just northeast of downtown, is one of Rochester's premier parks. The lake itself was created in the 1930s as part of a work project to create a recreational space, though a nearby power plant later used the lake for cooling. The plant shut down more than a decade ago.

Rochester has eyed improving the lake for years. A 2019 study showed tweaking the dam would allow for more fish and mussel migration over a 16.5 mile stretch of the Zumbro River. The city plans to dredge Silver Lake to remove sediment, tweak the dam to allow cascading pools as well as better control in case of flooding, and provide more walkable paths including a nearby pedestrian bridge and a trail extension.

Yet the project has stalled without funding. Workers were supposed to remove sediment from the lake last year, but that didn't happen. And while the city knows it will have to modify the dam, there aren't design plans in place showing what parts will be changed or removed.

Luckstein said the city is trying to schedule construction to take place all at the same time, contingent upon the Minnesota Legislature's approval this year of $2.6 million in Lessard-Sams funding.

Dam supporters say the city didn't follow state procedures to apply for that money, since the council didn't specifically approve of the proposal. But Luckstein points to a 2022 City Council decision to include the project in its state bonding requests, saying the council has reviewed the project several times in the past before making it a legislative priority.

Even if the city gets funding this year, it will take some time before work can start on Silver Lake. The city needs to go through project reviews with the U.S. Army Corp. of Engineers and the Minnesota Department of Natural Resources. Staff also need to hire consultants for project designs. And Rochester will have to work with the dam's status as a local landmark. Parts of the dam have historic protections and can't be altered.

Luckstein said the city doesn't expect to have shovels in the ground until 2026. And while critics argue the project won't expand fish migration because of similar dams nearby, Luckstein said the Silver Lake dam work could lead to similar projects to tweak other area dams.

Critics say they hope the city will be more forthcoming with information in the future. They take issue with some of the surveys city staff have done to garner support for the project, arguing the dam and lake changes could significantly change the area. They're concerned the city may extend its plans too far without oversight.

"That whole new system may not survive and the city might in the end say, well, just make it a river, and let's not worry about the rest of it." Munson said.