Columbia Lake is a lake near Portage in Columbia County, Wisconsin, United States. It is fed by the Wisconsin River and receives warm water discharged from a nearby power plant. As a result, the portion of the lake to the west of a dividing bank of earth is 70 to 85 °F or circa 20 to 30 °C year round, with a dense cover of fog in colder weather. This temperature prevents many types of lake weeds from growing. The lake is stocked with various types of fish and contains an uncommon hybrid bass.