St. Clair River
|Saint Clair River
Rivière Sainte Claire
Landsat satellite photo, showing Lake Saint Clair (center), as well as St. Clair River connecting it to Lake Huron (to the North) and Detroit River connecting it to Lake Erie (to the South)
|Mouth||Lake Saint Clair|
|Length||40.5 mi (65.2 km)|
|Avg. discharge||182,000 cu ft/s (5,200 m3/s)|
|Basin area||2,245 sq mi (5,810 km2)|
The St. Clair River is a 40.5-mile-long (65.2 km) river in central North America which drains Lake Huron into Lake St Clair, forming part of the international boundary between the Canadian province of Ontario and the U.S. state of Michigan. The river is a significant component in the Great Lakes Waterway, with shipping channels permitting cargo vessels to travel between the upper and lower Great Lakes.
The river, which some consider a "strait," flows in a southerly direction, connecting the southern end of Lake Huron to the northern end of Lake St. Clair. It branches into several channels near its mouth at Lake St. Clair, creating a broad delta region known as the St. Clair Flats.
The river is 40.5 miles (65.2 km) long and drops 5 feet (2 m) in elevation from Lake Huron to Lake St. Clair. The flow rate averages around 182,000 cubic feet per second (5,200 m3/s), and the drainage area is 2,245 square miles (5,810 km2). This takes into account the combined drainage areas of Lakes Huron, Michigan, and Superior.
In the 18th century, French Voyageurs and Coureurs des bois travelled on the river in canoes loaded with furs for Europe's royalty. Ships built at Marine City, Michigan, during the mid-19th century carried immigrants up the river on their way to new homes in the American West. During the 20th century, freighters returned from the upper Great Lakes with iron ore, copper, and grain - products of some of these settlers' labor.
The St. Clair River and its Lambton County tributaries in Ontario contributes 103,210 acres (41,770 ha) to the watershed, although this does not include the Sydenham River watershed. In Michigan, the Black River, Pine River, and Belle River drain 780,600 acres (315,900 ha) in Lapeer, Macomb, Sanilac, and St. Clair counties; the watersheds around Bunce Creek and Marine City are relatively small.
- Stag Island lies between Corunna, Ontario and Marysville, Michigan.
- Fawn Island is near Port Lambton, Ontario and Marine City, Michigan.
- Walpole, Seaway, Bassett, Squirrel, Pottowatamie, St. Anne, Dickinson, Russell and Harsens islands are located where the St. Clair River flows into Lake St. Clair near Algonac, Michigan; these islands form the "St. Clair Flats", the only major river delta in the Great Lakes and the largest freshwater delta in North America. Six of the islands in this delta are Crown lands used by the Walpole Island First Nation.
Land usage 
Most of the watershed away from the river in Ontario and Michigan is used for agriculture. A few forest and wetland remnants are present, although their area has declined significantly since European settlement.
Much of the shoreline on both sides of the St. Clair River is urbanized and heavily industrialized. Intensive development has occurred in and near the adjacent cities of Port Huron, Michigan and Sarnia, Ontario, at the northern end of the river. The heaviest concentration of industry (including a large petrochemical complex) lies along the Ontario shore south of Sarnia.
Several communities along the St. Clair rely on the river as their primary source of drinking water. About one-third to one-half of the residents of Michigan receive their water from the St. Clair/Detroit River waterway. Industries – including petroleum refineries, chemical manufacturers, paper mills, salt producers and electric power plants – need high quality water for their operations, although there have been some cases in recent years where these industries have contaminated river waters after discharging pollutants.
Land habitat 
Land areas of the St. Clair River shoreline and flats consist of two biological zones: upland and transitional, both of which are normally above the water table, but which may be flooded periodically.
The upland forests consist of deciduous species, many of which are near their northern climatic limit. Most pre-European settlement trees have been cleared for agriculture, industry, or urbanization. Remaining forest stands, such as oak savannas as well as lakeplain prairies, are found along the southern reaches of the river, particularly on the islands of the St. Clair River Delta and on the Michigan shore in Algonac State Park.
Transitional species are abundant in the low-lying regions, categorized as shrub ecotones, wet meadows, sedge marshes, and island shorelines and beaches. This habitat is home to water and land mammals, including humans, as well as songbirds, waterfowl, insects, pollinators, reptiles, and amphibians.
Water habitat 
Each area provides a unique habitat for aquatic life:
- macrophytes (visible marine plants),
- benthic macroinvertebrates (organisms that live at the bottom of a lake or stream),
- phytoplankton and zooplankton (floating plants and animals),
- emergent vegetation (plants seen above the water surface),
- fish (from minnows to large sport fish).
Area of concern 
The St. Clair River is listed as an Area of Concern (AOC) because of pollutants such as bacteria, heavy metals, and toxic organics, which had come from municipal and industrial discharges, urban and rural runoff, combined sewer overflows (CSOs), and contaminated sediments.
The St. Clair River AOC includes the entire river, from the Blue Water Bridge at the north end, to the southern tip of Seaway Island, west to St. Johns Marsh and east to include the north shore of Mitchells Bay on Lake St. Clair. Anchor Bay is not included.
Through the Great Lakes agreement, a Remedial Action Plan (RAP) was created to initiate cleanup measures. It consists of six steps:
- Restrictions on fish consumption
- Bird and animal deformities
- Degradation of benthos
- Restrictions on dredging activities
- Restrictions on drinking water consumption
- Beach closings
- Degradation of aesthetics
- Added cost to agriculture and industry
- Loss of fish and wildlife habitat
The RAP for the St. Clair River AOC was initiated in 1985. A binational group, called the RAP Team, was established in 1987 to develop the plan and ensure adequate and appropriate public involvement. The RAP Team included representatives from federal, state, and provincial governments.
- A large blob of perchloroethylene was found at the bottom of the St Clair River due to runoff from Dow Chemical Corp in 1985. It remains there, slowly mixing with the water.http://www.sustreport.org/lakes/lakes_timeline.htm#seventies
Erosion and Great Lakes Drainage 
Federal officials have long acknowledged that dredging and riverbed mining in the St. Clair dropped the long-term average of Great Lakes Huron and Michigan by about 16 inches. A Great Lakes water-level study recently completed by the U.S. and Canadian governments revealed that unexpected erosion since the last major St. Clair dredging project in the early 1960s dropped the lakes' long-term average by an additional 3 to 5 inches. Today, these lakes are nearly 2 feet lower than before human modifications to the riverbed of the St. Clair River.
|Harsens Island Ferry||M-154||Algonac, Michigan and Harsens Island, Michigan (crosses the North Channel of the St. Clair)|
|Russell Island Ferry||passengers only||Algonac, Michigan and Russell Island, Michigan|
|Walpole-Algonac Ferry||cars and passengers||Algonac, Michigan and Walpole Island, Ontario|
|Sombra-Marine City (Bluewater) Ferry||M-29
St. Clair Parkway
|Marine City, Michigan and Sombra, Ontario|
|St. Clair Tunnel||Canadian National Railway||Port Huron, Michigan and Sarnia, Ontario|
|Blue Water Bridge|| I-69
See also 
- U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed November 7, 2011
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