Lake Superior’s Physical Characteristics
Lake Superior is the greatest Great Lake – the largest freshwater lake in the world by surface area. Lake Superior could hold the water from all of the other Great Lakes, along with three more Lake Eries.
The lake contains three quadrillion (3,000,000,000,000,000) gallons of water. That's 10 percent of the world's fresh surface water, and over half of the water in the Great Lakes. Lake Superior contains enough water to submerge all of North & South America under one foot of water.
Of the Great Lakes, Superior is also the deepest; along much of Minnesota's North Shore the lake is 700 feet deep (213 meters) within 3 miles (4.8 kilometers) of land. The deepest spot, 1,332 feet (406) meters is 40 miles off of Munising, Michigan. Chicago's Sears Tower could sit at this depth with only a few floors sticking above the water.
If Lake Superior's shoreline were unraveled into a highway, it would extend 1,826 miles, the distance from Duluth to Miami. Lake Superior's watershed covers 49,300 square miles. A watershed is all land and water area that drain into the lake. Watersheds are often also called basins. This basin is small for the size of the lake.
For all its size, Lake Superior has less capacity to support aquatic life that do the other Great Lakes. Lake Superior is ultra-oligotrophic, which means it has less dissolved nutrients available to support aquatic life. As a result, the Lake Superior fishery produces only about 10 percent of what Lake Michigan, a comparatively nutrient-rich lake, produces annually.
Lake Superior’s fishery has improved tremendously during the last 25 years due to stocking, natural reproduction, and lamprey control. The health of the population has eliminated the need to stock lake trout in many areas of Lake Superior. Lake trout provide an excellent sport fishery and, in a few parts of Lake Superior, a viable commercial fishery.
In Minnesota, the commercial catch is limited to an assesment fishery: commercial gill-netters harvest a limited number of lake trout in exchange for providing biological information to the Minnesota Department of Natural Resources. Speces currently harvested from Lake Superior include lake trout, herring, chubs (deepwater ciscoes), siscowet (deep water lake trout), and smelt. Both trout and salmon support a viable charter and recreational fishign fleet that contributes significantly to the region's economy.