Private hatchery operators also use aeration systems, usually on small lakes without public accesses. Caution is urged when going onto any ice-covered lake, particularly at night. Leaks may develop in air lines creating other areas of weak ice or open water.
Aeration systems help prevent fish winter kill by adding oxygen to lakes.
They also create areas of open water and thin ice that are significant hazards to ice anglers, snowmobilers, skiers and other lake users. They are generally operated from the time the lakes freeze until the ice breaks up in the spring. The majority of the aeration systems are located in counties in the southern and western portions of the state. A DNR permit is required to install and operate an aeration system. Permit holders must publish public notices, post warning signs and inspect the systems at least once every seven days.