Cottage Grove allows riverbed mine proposal to advance

At its November 5, 2025 meeting, the Cottage Grove City Council voted to approve the Environmental Impact Statement for a proposed gravel mine in the Mississippi River bottom. 

The Environmental Impact Statement does not grant permission to mine, but it is an important advisory document to guide future decision-making about the project.

Amrize (formerly known as Holcim Industries) aims to dig a 200-foot-deep mine pit in the riverbed to extract aggregate — sand and gravel — next to its current upland mine on Lower Grey Cloud Island.

Read more about the proposed mine and watch WCCO's recent piece on community pushback to the project.

Damaging impacts and questionable legality

In early 2025, during the public comment period for the draft Environmental Impact Statement of this project, several government agencies, Cottage Grove residents and Friends of the Mississippi River (FMR) raised numerous concerns.

Agencies expressing legal concerns with the Environmental Impact Statement include Dakota County, the Metropolitan Council, the DNR, the Minnesota Indian Affairs Council, the U.S. Army Corps of Engineers, and the National Park Service.

Commenters pointed out that the proposed mine would damage wetlands, mussel beds, and rare plant communities; reduce backwater access for boaters, hunters, and anglers; and increase noise and visual pollution in local parks and neighborhoods.

The Prairie Island Indian Community also noted "a complete disregard for the likely presence of burials and cultural resources in the project area," given that the area was a significant Dakota village site and has numerous burial mounds. (Prior mining has destroyed many, but not all, of these mounds.)

In addition, FMR questioned the legality of a riverbed mine. The Minnesota Department of Natural Resources (DNR), the National Park Service, and the Minnesota Center for Environmental Advocacy joined FMR in stating that the state's Mississippi River Corridor Critical Area regulations (which FMR spent years working to bring about) prohibit shoreline mining like what Amrize proposes.

The city of Cottage Grove pushed back on our initial comments. So FMR recently submitted another letter, again pointing out the illegality of mining in a shoreline area protected by the critical area rules. The DNR also submitted another letter.

Other agencies have noted additional possible legal issues. The Environmental Impact Statement's project goals are too narrow: to extend the life of the existing Amrize mine site, barge network and distribution systems, and to do so at the lowest cost to the company. This narrow purpose eliminates any alternative that isn't in this backwater area and prioritizes one company's profits over the public interest in a clean and healthy Mississippi River. The impact statement fails to document the impacts and mitigation plans fully.

Another potential legal issue is that the proposed mine would be in a public waterway. This site is unusual in that the riverbed is privately owned — a rare holdover from when the area was upland before Lock and Dam 2 was built downstream. Regardless of who owns the riverbed, the river above it is public and subject to public waters regulations. There are no other active aggregate mine sites in Minnesota's public waters.

Cottage Grove council response

The Cottage Grove City Council approved the Environmental Impact Statement as adequate, meaning that the city believes it meets the state's required level of thoroughness and accuracy. FMR Executive Director Whitney Clark joined residents in speaking at the city council meeting.

Responding to community and agency feedback, Mayor Myron Bailey read a statement pointing out that the significance of the Environmental Impact Statement is only one step in the process. Several other agencies will have final permitting authority.

What's ahead

If parties continue to believe that the city's adequacy determination of the Environmental Impact Statement was incorrect, given the numerous legal issues with the proposed mine, costly lawsuits could potentially be on the horizon.

Before any mining takes place, Amrize must still obtain permits from the city, the DNR, the U.S. Army Corps of Engineers and other agencies. Due to its severe environmental impacts, this project may not be able to meet all the permitting requirements.

Because Grey Cloud Island is important to Dakota people, we also expect more thorough consultation with Tribal Nations before any permits can be issued. 

FMR will continue to monitor this project closely throughout the various permitting processes ahead. We will work with our partners to ensure that Cottage Grove follows the laws designed to protect the Mississippi River.