Drawdown will facilitate repairs while improving habitat and water quality
Repair work and upgrades are underway on the dam at the outlet of Heron Lake. As part of that work, a lake drawdown is being performed to facilitate access to equipment and infrastructure. Contractors are replacing the hydraulic and electrical systems that control the gate on the dam.
Following completion of this work, wildlife managers with the Minnesota Department of Natural Resources plan to keep Heron Lake water levels low through summer 2024 to improve water quality and reestablish aquatic vegetation on this very important waterfowl resting area.
“The management plan for Heron Lake was completed at the end of 2021, and it includes several triggers for management actions,” said Brian Nyborg, Windom area wildlife manager. “The current habitat conditions in Heron Lake call for implementing a drawdown on the basin this winter.”
Those conditions include water clarity of less than a foot, poor diversity of plant species and abundant populations of common carp.
A lake drawdown mimics a drought, which can reset an ecosystem by removing carp populations, consolidating sediment suspended in the lake water, and allowing the reestablishment of aquatic vegetation. In spite of two years of drought conditions, the lake’s sizeable watershed prevented a full drawdown of the lake. Utilizing the dam to achieve a full drawdown in future years will help improve habitat. Its benefits include establishing lakeshore vegetation, which will also help mitigate erosion since Heron Lake is susceptible to wind and wave action.
Heron Lake is nearly 8,000 acres in size and was designated as a wildlife lake in 1973. This designation allows Minnesota DNR wildlife managers to take action to mitigate factors that affect water and habitat quality and quantity. Temporary drawdowns are a common management tool to improve lake habitat conditions for wildlife. Information on designating wildlife lakes is available on the DNR website.
The project is funded by the DNR’s waterfowl stamp fund, the Outdoor Heritage Fund and the natural resources asset preservation bonding fund.