There have been many reports about the remarkable amount of ice coverage on the Great Lakes during this frigid winter. The highest recorded total ice coverage on the Great Lakes is 94.7% from 1979 (the most modern data set only goes back to 1973).
On February 12, the Great Lakes were 87% sealed with ice.
Ice builds around Chicago's water intake
A witness to the freeze on Chicago's Navy Pier
Check out the remarkable growth of ice on Lake Michigan over a 4-day period this month here.
Prevailing winds from the west tend to break up Lake Michigan's ice and push it across the lake to the shores of Indiana and Michigan. Large stacks of ice form along the shoreline.
Ice builds around Navy Pier
Ice floe meanders up the Chicago River
The ice coverage will reduce the amount of water that the lakes lose to evaporation this spring. Heavy precipitation this winter will flow to the lakes and raise them up to 11" this year.