||Lake Superior is the fourth largest lake in the world by volume, exceeded only by the Caspian, Baikal and Tanganyika. Superior is the largest, deepest and coldest Laurentian Great Lake.
Although water quality has improved dramatically from the eutrophic conditions in the 1970's, and there is much greater regulation of point-source pollution, Lake Superior still faces significant challenges in tackling non-point source pollution, invasives, high concentrations of toxic chemicals and habitat alteration.
Climate change is also affecting the lake. Superior is one of the most rapidly warming lakes in the world. Measured evaporation rates are on the rise. The lake has lost 79% of its ice cover and lake levels have fluctuated below the long-term average since an extreme event weather event in 1997-98.