DNR to temporarily lower Silver Lake water levels (published July 22, 2024)

The Minnesota Department of Natural Resources will begin to temporarily lower the water levels of Silver Lake in Sibley County to improve water quality and fish and wildlife habitat. The 697-acre lake has been overwhelmed by large populations of common carp, causing turbid water and impeding aquatic plant growth.

Common carp can have a negative impact on water quality when they uproot native plants and disturb phosphorous-rich bottom sediments through their feeding habits. Minnesota Pollution Control Agency Citizen Lake monitoring data from June 2008 to September 2017 found that Silver Lake had phosphorus levels more than four times the level that delineates an impaired water from non-impaired.

A 2022 survey of Silver Lake found the lake was nearly devoid of submerged aquatic vegetation, which plays an important role in maintaining water clarity and fish and wildlife habitat. Both indicators were a significant decline from a survey in 2015.

The planned drawdown will lower water levels to mimic a drought, acting as a natural “reset” to a shallow lake ecosystem. Unless future rainfall keeps water levels too high, the drawdown will begin in the current open water season and continue into 2025.

The management plan calls for the lowering of water levels to a depth of about 2 feet to create conditions for a winterkill and reduce common carp populations. The drawdown will also allow sediments to consolidate, which will permit new growth of submerged and emergent vegetation. Following the drawdown, the Minnesota DNR will stock walleye fry in Silver Lake in alternate years and continue to assess winterkill severity from either managed drawdowns or natural winterkill events.

Anyone with questions about the Silver Lake project can contact Tim Koppelman, assistant area wildlife manager at [email protected] or at 507-386-3923 or Steve Kittelson, wildlife lake specialist, at [email protected] or 507-578-8891. Fisheries questions can be directed to Scott Mackenthun, area fisheries supervisor, at [email protected] or 320-753-0324.