BARRON, Wis. (AP) State environmental officials are warning people to be careful of open water on two dozen or so northern Wisconsin lakes.

Department of Natural Resources officials say lakes in Barron, Burnett, Polk and Washburn counties have aeration systems in them this winter. The systems are designed to pump more oxygen into the water, preventing large fish winter kills. But the systems also cause areas of the lakes to stay ice-free.

Brian Spangler is a DNR fisheries technician. He says the open areas should be surrounded by a fence or reflectors, but snowmobilers, anglers and other ice users still should use extra caution.

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