Ice Out: 39 Degrees of Magic

May 6, 2005 By: Marshall Cutchin

Ed Dentry looks at the phenomenon of ice-out and explains why the warming of ice-bound lakes and rivers briefly makes fishing so good. “Water is heaviest at 39 degrees and lighter when it is warmer or colder. During ice-fishing season, the heaviest water (39 degrees) will be at the bottom of a lake and the water column from bottom to the ice lid will be about 32 degrees. When the ice melts, sun and wind quickly warm and oxygenate the 32-degree surface. When surface waters reach 39 degrees (heaviest), they sink to the bottom, dragging oxygen along and mixing with 39-degree water down deep.” In the Rocky Mountain News.