The Brown County Sheriff’s Office has issued a thin ice warning for area lakes. Brown County Sheriff Rich Hoffmann would like to remind residents of the Brown County Ordinance regarding driving on lakes that have aeration systems. Aeration systems cause thin ice areas that are unstable and unsafe to drive a motor vehicle on. Motor vehicles, including snowmobiles, are prohibited from driving in areas marked with warning signs indicating aeration system in use and thin ice warnings. Brown County waters affected by aeration systems are Clear Lake, Lake Hanska, Sleepy Eye Lake and the Wellner/Hageman Reservoir.