JOHNSON COUNTY, Iowa -The public is being advised to stay off the ice at Coralville Lake.
The Army Corps of Engineers is warning of unstable ice, and telling ice fishermen and snowmobilers to stay off the ice and use extreme caution along the shoreline.
An advisory says water levels on the lake can fluctuate and cause the ice to weaken if those levels drop.
It says Coralville Lake's ice is vastly different from smaller ponds and even Lake Macbride.
Frozen portions of Coralville Lake may no longer be supported if the water is low and could give way at any time.