Lake Superior

Lake Superior is the northernmost Great Lake. The lake borders Minnesota, Wisconsin, Michigan’s Upper Peninsula, and the Canadian province of Ontario. About 200 rivers feed into Lake Superior, and the average drop of water will travel around the lake for 191 years before exiting through the Soo Locks on the St. Marys River.

Learn much more about Lake Superior’s glacial history, water budget, weather and climate, and human interactions from Minnesota Sea Grant.

Lake Superior

Lake Superior basin statistics


  • Length: 350 mi (563 km)
  • Breadth: 160 mi (257 km)
  • Elevation: 600 ft (183 m)
  • Depth: 483 ft (147 m) average; 1,330 ft (406 m) maximum
  • Volume: 2,900 cubic mi (12,100 cubic km)
  • Water surface area: 31,700 square mi (82,100 square km)
  • Drainage basin area: 49,300 square mi (127,700 square km)
  • Shoreline length: 2,726 mi (4,385 km), including islands
  • Outlet: St. Marys River to Lake Huron
  • Retention or replacement time: 191 years

Ecology

Known for its sparkling waves and rugged shorelines, Lake Superior contains more water than the other Great Lakes combined. Superior is the northernmost lake and the least affected by invasive species, habitat degradation, and other human-driven changes. The deepest and coldest Great Lake, Superior’s nutrient-poor waters have allowed native coldwater fishes to flourish.

The watershed is dominated by the Canadian Shield, noted for its ancient rocky outcroppings and thin, nutrient-poor soil. The Canadian Shield does not include the limestone bedrock common in watersheds to the south. Without the steady weathering of limestone, Lake Superior’s waters are too calcium-poor to sustain a large population of invasive quagga mussels, which build their shells with calcium carbonate dissolved in lake water.

Fisheries

Lake Superior’s cold, clear water is ideal for native ciscoes and lake trout. Lake Superior supports 52 fish species, fewer than any other Great Lake, in part because other lakes offer more diverse temperatures and habitats.

Unlike other lakes, Lake Superior’s native species retain the upper hand over invasive and introduced species. Ciscoes and their relatives provide an important link between zooplankton and predatory fish. The only abundant invasive plankton-eating fish is the rainbow smelt.

Lean lake trout are the backbone of recreational fisheries in offshore waters of Lake Superior. Bold anglers can find huge lake trout near sunken islands and rock reefs. Stannard Rock north of Marquette, Michigan, is one such destination that has produced fish weighing over 60 pounds. While trolling is typically the preferred method of lake trout fishing in the Great Lakes, Lake Superior also offers good opportunities for jigging.

Harbor areas and protected bays like Duluth Harbor and Tahquamenon Bay offer some opportunities for coolwater fish like pike, walleye, and perch. Introduced coho salmon and steelhead also provide fisheries near river mouths. Although these species were originally stocked, natural reproduction in Lake Superior rivers is now high enough to sustain populations.

Lake Superior’s commercial fisheries target lake whitefish, lake trout, and ciscoes. The largest market for cisco (also called lake herring) is for roe (eggs) exported to Scandinavian countries. Cisco and bloater are also sold as “smoked chubs” at many roadside fish markets around Lake Superior.

Communities

Lake Superior’s mostly rural communities are spread across a forested and largely undeveloped landscape. Timber and mining industries are important economic drivers, notably copper mining in the Keweenaw Peninsula. The lingering environmental effects of mining operations continue to cause water quality and community development problems.

Duluth, Minnesota (U.S.), is an important commercial shipping port for exporting agricultural products from the interior United States. Duluth and other commercial ports are often unintentional introduction points for invasive species carried in cargo ship ballast water.

Other major community centers include Marquette, Michigan (U.S.), Sault Ste. Marie, Michigan (U.S.), and Sault Ste. Marie, Ontario (Canada), where the St. Marys River connects Lake Superior with Lake Huron. A sizeable Native American community fishes in Lake Superior under treaty agreements; commercial fishing by the tribal fleet and other vessels plays an important economic role in the region. Recreational fishing and tourism also draw dollars to Lake Superior.