Lake Dubay is a 6,700-acre hydroelectric reservoir formed by damming the Wisconsin River, located in Marathon and Portage Counties in Wisconsin. Created in 1942 for hydroelectric generation and flood control, it's the fourteenth largest inland body of water in Wisconsin with approximately 42.3 shoreline miles and a maximum depth of 30 feet. The reservoir has 12 inlets, with the Wisconsin, Big Eau Pleine, and Little Eau Pleine rivers being the major ones. The water is dark stained and turbid at times, with a mostly sand bottom complemented by shoreline timber, sunken wood, and many stump fields. Lake Dubay is classified as a eutrophic lake with high phosphorus and chlorophyll levels, which leads to seasonal algal blooms, particularly in midsummer. Aquatic vegetation is generally scarce and low density due to limited light penetration.