The Minnesota DNR urges people to stay off the ice all winter at the Canisteo pit, nearby wetlands, and Holman Lake
The Minnesota Department of Natural Resources has resumed seasonal pumping to control water levels at the Canisteo Legacy Mine Pit (Canisteo) in Itasca County. Pumping this winter will keep water levels below 1,318 feet. Maintaining water levels below 1,318 feet ensures that the drain tile system continues to divert groundwater away from residential structures located in Bovey. Additionally, lowering water levels as much as possible this winter is essential to preparing for the construction of a permanent outlet structure.
The pumping system is located on the east side of the Canisteo and draws water from the pit at a maximum rate of 18,000 gallons per minute. Pumping is occurring at a higher rate than last year to prepare for construction of the permanent outlet. The water will be discharged to a wetland complex that flows into Holman Lake in Itasca County.
Once pumping begins, the Canisteo water level is expected to drop, which could create a gap between winter ice cover and the water’s surface below, resulting in unsafe ice conditions across the entire pit. Water from the Canisteo will flow into the nearby wetlands and Holman Lake, potentially resulting in unsafe ice conditions on those water bodies. The DNR strongly advises that all people and recreational vehicles stay off the ice all winter at the Canisteo, nearby wetlands, and Holman Lake.
Active mining in the Canisteo stopped in 1980 and no company is responsible for managing the Canisteo’s rising water levels. As of November 2023, the Canisteo water level is around 1,310 feet, which is 14 feet below natural overflow. Until an engineered outlet is in place, seasonal pumping is being used to control Canisteo water levels.
To prevent the spread of invasive species downstream, the DNR must ensure that zebra mussel larvae, called veligers, are not present in the Canisteo before water is discharged into surrounding water bodies. Water sampling has documented that zebra mussel’s reproductive season ends during winter months when water temperatures are consistently below 53 degrees. When water temperatures are low, live veligers, which float in the water and can be moved by water currents, are not present in the water column. Therefore, confining pumping to the winter months avoids the expense of additional filtration or treatment.
The 2023 legislature approved $8.875 million dollars for construction of an outlet at the Canisteo to provide permanent and year-round water level management. The permanent outlet will address removal of invasive species. The permanent outlet project will go out for bid in spring 2024, and construction could start later that year.
More information is available on the DNR’s Canisteo Mine Pit webpage.