The St. Marys River (French:rivière Sainte-Marie), sometimes written as the St. Mary's River, drains Lake Superior, starting at the end of Whitefish Bay and flowing 120 km (74.5 miles) southeast into Lake Huron.
For its entire length it is an international border, separating Michigan in the United States from Ontario, Canada.
The most important area along the river are the rapids and the twin cities of Sault Ste. Marie, Ontario and Sault Ste. Marie, Michigan, with the most famous man-made feature being the Soo Locks.
The rapids of the St. Mary's (Sault Sainte Marie in French) are just below the river's exit from Lake Superior.
Two of the Ontario tributaries of this river are the Garden River and the Bar River. Other Canadian tributaries include: Fort Creek, Root River, Little Carp River, Big Carp River, Lower Echo River, Desbarats River, and the Two Tree River. The American tributaries to the St. Mary's River are: Gogomain River, Munuscong River, Little Munuscong River, Brimley River, and the Charlotte River.
Before Europeans arrived, native Americans fished, traded, and maintained a portage around the rapids. French
explorer Étienne Brûlé
was the first European to travel up the rapids in about 1621. In 1641 Jesuit
priests Isaac Jogues
and Charles Raymbault
ventured the same route as Brûlé finding many Ojibwa
at the rapids and named it Sault Ste. Marie
meaning "rapids" in French).
Fort St. Joseph was built on the Canadian shore in 1796 to protect a trading post, and ensure continued British control of the area.
The fort fulfilled its role in the War of 1812.
The first modern lock was completed in May 1855 by Erastus Corning's St. Mary's Falls Ship Canal Company, and is known as the American Lock.
Competitive pressure led to the construction of a Canadian Lock in 1895.
The locks were made a part of the Great Lakes Waterway system in 1959 known as the Soo Locks.
The Sault Ste. Marie International Bridge
, a steel truss arch bridge
takes road traffic across the river. Directly to the west is the Sault Ste. Marie International Railroad Bridge
which carries rail traffic on a single set of tracks.
The Edison Sault Electric Hydroelectric Plant, located at the eastern end of the Saulte Ste. Marie Power Canal which runs between Lake Superior and Lake Huron through the city south of the American locks, is the longest hydroelectric
plant in the world at 1,340 ft
) in length. The plant consists of 74 three-phase generators capable of generating 25 to 30 MW
. It was completed in 1902, and consists mostly of the stone left over from the excavation of the Sault Ste. Marie Power Canal.
The United States Army Corps of Engineers owns and operates a hydroelectric generating plant directly north of the American locks.
Finally, the Francis H. Clergue Generating Station, owned and operated by Brookfield Renewable Energy, Inc., is a hydroelectric generating plant located directly north of the Canadian lock with a generating capacity of 52 MW. It was completed in 1981.
The Edison Sault Power Canal is used to power the Edison Sault Electric Hydroelectric Plant at its eastern end. The canal seperated downtown Sault Ste. Marie, Michigan from its mainland making it an island. It was begun in September 1898 as the Michigan Lake Superior Power Company Canal, but completed by Edison Sault Electric Company in June 1902. Measured from its headgates to its end at the power plant, is is 2.25 mi
) in length, between 200 ft
) and 220 ft (67 m) wide, and 24 ft (7.3 m) deep. The water runs down the canal at speeds upwards of 7 MPH
Main Article: Soo Locks
The Soo Locks are located on the north and south sides of the river.
A set of compensating works are located at the mouth of the rapids, which are used to control the outflow of water from Lake Superior. The works consists of 16 gates, half of which are on the American side, and the other half on the Canadian side of the river. They were completed between 1901 and 1921. This flow is controlled by the International Joint Commission
A concrete berm was constructed along the north side of the rapids as remedial works to protect fish spawning habitat from lower outflow through the rapids. This was due, in part, by an increase of water outflow from the Francis H. Clergue Generating Station.
The Saint Marys River is listed as a Great Lakes Areas of Concern
in The Great Lakes Water Quality Agreement between the United States and Canada.