The Iowa Department of Natural Resources has turned on the winter aeration systems at area lakes in Winnebago, Hancock, Worth, Kossuth, and Wright Counties. Winnebago County Conservation has also turned on their aerators at Lake Catherine and other locations. Crystal Lake has theirs running until the ice clears in the spring.
The aerators are designed to reduce the chance of a winter fish kill due to low dissolved oxygen levels in the lake. Oxygen is not injected into the water with the aeration system, but there is an exchange of oxygen when the air hits the open water. The aerators create open areas where fish can go when oxygen levels start to decline.
Aeration holes are marked with thin ice perimeter signs. Lake users should avoid the open water around the aerators. Unsafe ice will vary depending on the weather. Always check the ice conditions before you venture away from the shoreline.