A project is underway to permanently prevent the Canisteo Mine Pit in northern Minnesota from overflowing into the nearby city of Bovey.

The pit — actually multiple former mine sites that merged as they filled with water — has seen the water level rise 5 to 7 feet each year, the state Department of Natural Resources says.

Bovey is directly south of the 5-mile-long pit and near one of the first spots where water could overflow.

The DNR has managed water levels by pumping more than 4.7 billion gallons from the Itasca County site and is now building an outlet. When finished, it will allow water to flow to the Prairie River, maintaining Canisteo's levels year-round without relying on seasonal pumping.

Work should be mostly complete by August, the DNR said.

In 2023, the Legislature approved nearly $9 million to build the outlet and its complex sand-filtration system.

The automated system will capture invasive species, such as zebra mussels, to prevent them from entering the river.

Groundwater and precipitation have filled the pit since mining operations ceased, and no company is responsible for managing the levels, the DNR said.

In 2022, the Department of Iron Range Resources and Rehabilitation funded a water-pumping project managed by the DNR.

The 4.7 billion gallons of water pumped from the pit went to Holman Lake and a wetland complex. Winter pumping has kept levels low enough to prevent flooding.

The DNR does not plan to open public access to the pit.