Ice fishing on Monona Bay on a frigid January morning. A spokesperson for the city’s fire department says ‘no ice is safe ice.’. On a recent bright Friday morning, people were fishing by their ice shanties on frozen-over Monona Bay. Ice thickness on the bay’s west side on Jan. 3, according to users on the freshwater fishing forum Lake-Link, was around 4 to 5 inches, above the recommended 4-inch minimum for walking on ice.