
The late spring allowed the large lake (17 miles North/South by 13 miles East/West) to hold on to its protective ice covering longer than normal. Now add in winds of 35mph with gusts up to 50mph and something's got to give. Lake Mille Lacs is shallow for its size with an average depth of 35ft so it often acts like a dishpan with water sloshing from side to side like a tidal action. This unusual phenomena will occur about once every 25 years allowing the builders to encroach ever closer to the lake as the memories fade.
A steep rocky shore allows the ice to pile up as high as 50ft in places, but if the shore's tapered, the ice creeps hundreds of feet from the shore line (and tearing up out-buildings) as can be seen in the video. Listen closely to the sounds of the ice moving, at times it sounds like an old locomotive chuffing along.
https://www.youtube.com/watch?v=0EyfEDKWscg&sns=em