Lake Superior

Lake Superior Overview


Lake Superior is the largest freshwater lake in the world by surface area.   It is the world's third-largest freshwater lake by volume and contains nearly 10% of the word’s fresh surface water.  Lake Superior is relatively young, approximately 10,000 years old dating back to the last glacial retreat.  The Lake Superior watershed includes the surrounding areas of Ontario, Minnesota, Wisconsin and Michigan.

Lake Superior has a surface area of 31,820 square miles (82,413 km2), which is approximately the size of South Carolina. It has a maximum length of 350 miles (563 km) and maximum breadth of 160 miles (257 km). Its average depth is 482 feet (147 m) with a maximum depth of 1,332 feet (406 m). Lake Superior contains 2,900 cubic miles (12,100 km³) of water. There is enough water in Lake Superior to cover the entire land mass of North and South America with 1 foot (30 cm) of water. The shoreline of the lake stretches 2,726 miles (4,387 km) (including islands).  More than 300 streams and rivers flow into Lake Superior, the largest tributaries include the Nipigon River in Ontario, Canada, and the St. Louis River in Minnesota.  Lake Superior drains into Lake Huron via the St. Mary’s River. 

Lake Superior is an oligotrophic lake with fewer dissolved nutrients relative to its water volume producing fewer fish compared to the other Great Lakes. Lake Superior is home to over 80 species of fish (17 native and 15 non-native species). Native species caught for commercial fishing include lake herring (cicso), Lake Whitefish and lake trout. Some non-native species have become a  part of the commercial fishing industry in the lake including rainbow and brown trout which were intentionally introduced in the early 1900s.   Over the past 40 years there have been marked improvements in the health of Lake Superior's fishery however challenges remain with the impacts from aquatic invative species, habitat destruction, coastal development, pollution and impacts from a changing climate.  

The population in the Lake Superior Basin on the U.S. side is 425,548 and 181,573 in Canada. The basin features many rural communities with a few small cities including Duluth, Minnesota, Superior, Wisconsin and Thunder Bay, Ontario. Most of the Lake Superior basin area is heavily forested and economically dependent on the abundance of natural resources and tourism with over 3.5 million visitors per year. 


Surface Area 31,700 miles2 82,100 km2
Maximum Depth 1,826 miles 2,938 km
Watershed Area 49,300 miles2 127,700 km2
# of Fish Species 86*  
Water Retention/Replacement Time 191 years  

 *71 native, 15 non-native



Links to other resources

Great Lakes Atlas - U.S. EPA


Lake Superior Basin Land Use