The DNR communications team works with agency experts to develop the weekly questions and provide the answers. This feature addresses current DNR issues, interesting topics, or the most frequently asked questions from around Minnesota.
Q: How does the DNR decide whether to aerate a lake to prevent winter fish kill?
A: The DNR does not aerate lakes, but we do issue permits to lake associations, counties and other local partners who wish to aerate shallow lakes that are prone to fish kills due to lack of dissolved oxygen during winter. Public safety is the primary concern, so these permits require aerated parts of the lake to be clearly marked with thin ice signs and located away from high-traffic areas such as boat launches and snowmobile trails.
DNR fisheries and wildlife managers often provide guidance on whether or not aeration is desirable for a given lake. For example, some shallow lakes are important habitat for waterfowl, where fish compete with ducks and geese for food while stirring up sediment that can harm aquatic vegetation. In those cases, natural winter fish kills serve an important biological purpose.
Marilyn Danks, DNR aeration program specialist