Lake Mendota declared to be frozen over after storm system brings strong winds, bitter cold

To be considered frozen over, lakes Wingra and Monona must have at least half ice cover. Mendota, the largest of Madison’s lakes, is subject to another rule developed by limnologists Edward Birge and Chancey Juday in the early 1900s: If you can’t row a boat between Picnic Point on UW-Madison’s northeast side to Maple Bluff, the lake is frozen.