The Minnesota Department of Natural Resources has turned off the water pumps at the Canisteo Mine Pit, marking the end of a second season of winter contingency pumping. For the last two winters into early springtime, water pumping operations ran 24 hours a day to reduce the water level in the Canisteo pit and prevent it from overtopping.

During this pumping season, the water levels in Canisteo have dropped from 1,309.53 to 1,303.65. As a result, the water level is now nearly six feet lower than last year. Since seasonal pumping began two years ago, more than five billion gallons of water have been discharged from the Canisteo into a nearby wetland complex and Holman Lake, decreasing water levels in the pit by eight feet.

The contingency pumping project had a specific goal, which was to maintain the water levels of Canisteo below 1,318 feet. Keeping the water below this level ensures that the City of Bovey drain tile system continues to effectively direct water away from residential structures. The project also aimed to prevent the spread of aquatic invasive species downstream, particularly zebra mussels, by pumping only during cold water conditions.

On May 10, the DNR halted the water pumping activities in Canisteo because water temperatures in the pit had reached 48 degrees for four consecutive days. When the water temperature rises to 50 degrees or higher, zebra mussels reproduce. During reproduction, immature zebra mussels called veligers, may be present throughout the water column. Turning off the pumps before zebra mussels start to reproduce helps prevent the spread of veligers to the wetland complex and Holman Lake.

The Canisteo contingency pumping project was the first step in building a permanent water outflow for the pit. The 2023 Minnesota Legislature approved $8.875 million in bonding funds to construct an outlet at Canisteo. The outlet is designed as a natural gravity outflow system with sand filtration built-in to prevent the transfer of zebra mussels to downstream water bodies. When completed, the natural outflow structure will flow into the Prairie River and provide year-round water level management, which will eliminate the need for seasonal pumping.

The construction contract for the outlet structure will soon be put out for bid, and work could begin as early as this summer. People can learn more about the Canisteo water management project at the DNR website.