(1) Chart Datum, St. Clair River.- Depths and vertical clearances
under overhead cables and bridges given in the chapter are referred to the sloaping
surface of the river corresponding to a Lake Huron Stage of 577.5 feet (176.0 meters) and
a Lake St. Clair Stage of 572.3 feet (174.4 meters) above mean water level at Rimouski,
Quebec, on International Great Lakes Datum 1985 (IGLD 1985), which elevations are the
planes of low water datum for the two lakes. (See chart datum, Great Lakes System, indexed
as such, chapter 1.)
(2) General Description.- St. Clair River is about 39 miles long from Lake St. Clair via St. Clair Cutoff Channel and South Channel to the head of the river at Lake Huron. The lower 11 miles of the river is a broad delta through which numerous channels flow into Lake St. Clair. South Channel and St. Clair Cutoff Channel form the main navigation route through the delta and connect with the dredged channel across Lake St. Clair. The upper river, above Chenal Ecarte, is generally a single deep channel, except where obstructed by Fawn Island and Stag Island. The banks of the river are clay and sand and usually quite steep.
(3) Channels.-The channel through St. Clair River has been improved in places by dredging. The federal project depth in the river is 27 feet.
(4) Fluctuations of water level.-Each year the St. Clair River has a seasonal rise and fall of about 1 foot, generally in consonance with the seasonal variations of Lake Huron. High winds may cause rapid fluctuations of up to 2 feet above or below normal.
(5) Currents,St. Clair River.-The following currents are based on averages of water flow through through the entire cross section of the river, that is from bank to bank and from surface to bottom during normal flow conditions. Normal flow conditions are encountered when there is no wind, Lake Huron is at a stage of 578.9 feet (176.4 meters) and Lake St. Clair is at a stage of 573.9 feet (174.9 meters) above the mean water level at Rimouski, Quebec, on the International Great Lakes Datum 1985 (IGLD 1985), that is 1.4 feet (0.4 meter) and 1.6 feet (0.5 meter) above their respective Low Water Datums. The current encountered at midstream is usually about 1.5 times the average velocity. Greater Velocities may be expected when the difference between lake levels is greater, or the lake stages higher.
(6) Currents for the following locations in the St. Clair River are given at high water flow of 230,000 cubic feet per second (cfs), medium water flow of 188,000 cfs, and low water flow of 130,000 cfs, respectively.
(7) Algonac: 2.0 mph, 1.6 mph, and 1.3 mph.
(8) Port Lambton: 2.0 mph, 1.7 mph, and 1.3 mph.
(9) Marine City: 2.0 mph, 1.6 mph, and 1.3 mph.
(10) St. Clair: 2.1 mph, 1.8 mph, and 1.4 mph.
(11) Marysville: 1.9 mph, 1.6 mph, and 1.3 mph.
(12) Point Edward: 3.9 mph, 3.3mph, and 2.5 mph.
(13) The rapids section extends from about 1,00 feet above to 200 or 300 feet below the Blue Water Bridge. During peroiods of sustained high N to NE winds on Lake Huron, velocities in the upper St. Clair River are increased.
(14) Ice.- The only need for ice breaking in the St. Clair River occurs when the ice bridge that form across the S end of Lake Huron breaks and the broken mass of ice travels down the river to the lower end where it meeets the natural ice cover and forms a massive ice jam. When this occurs, ice can clog the entire 27-foot depth of the channel and cause serious flooding. (See winter navigation, chapter 3.)
(15) Navigation Regulation.-The State of MIchigan enforces the following speed limits for recreational craft within its jurisdictional boundaries from the mouth of the Black River down stream to the mouth of the St. Clair River: slow-no wake for vessels less than 26 feet long within 200 feet of any shore, dock, or pierhead, and slow-no wake for vessels 26 feet or longer within 600 feet of any shore, dock, or pierhead.
(16) A vessel traffic reporting system and related navigation regulations have been established for the connecting waters from Lake Erie to Lake Huron. (See 33 CFR 162.130 through 162.140, chapter 2, for regulations.)
(17) Vessel Traffic Service.-The Canadian Coast Guard operates a Vessel Traffic Service in Canadian waters from Long Point in Lake Erie through the Detroit and St. Clair Rivers to De Tour Reef Light in Lake Huron. (See Chapter 3 and the Annual Edition of Canadian Notices to Mariners for complete information.)
(18) Pilotage.-The waters of St. Clair River are Great Lakes designated waters; registered vessels of the United States and foreign vessels are required to have in their service a United States or Canadian registered pilot. Registered pilots for St. Clair River are supplied by the Lakes Pilots Association. Pilot exchange points are just below the Ambassador bridge in Detroit River and off Port Huron at the head of the St. Clair River in about 43 05'30"N.,82 24'42"w. The pilot boat in the Detroit River , J.W. Westcott II, has a black hull encircled by an orange band and a white cabin with the words "U.S. Mail" in black letters. Three pilot boats are at Port Huron: Huron Belle has an international orange hull with an aluminum cabin, and Huron Maid and Huron Lady each have an international orange hull with a white cabin. (See pilotage, chapter 3, and 46 CFR 401, chapter 2.)
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