Lake Frontenac was a proglacial lake in the basin of what is now Lake Ontario. The sudden influx of fresh water into the Atlantic, as the retreat of the Laurentian Glacier triggered a sudden drop in the lake's water level, may in turn have triggered the onset of the Younger Dryas, 1000-year period of renewed cooling approximately 12000 years ago.
Map of Frontenac Lake, Rockwood Township, MN 56601, USA
References
Lake Frontenac Wikipedia(Text) CC BY-SA