(1) Chart Datum, Lake St. Clair.- Depths and verticle clearances are
given in this chapter are referred to Low Water Datum, which for Lake St. Clair is an
elevation of 572.3 feet (174.4 meters) above mean water level at Rimouski, Quebec, on
International Great Lakes Datum 1985.(See Chart Datum, Great Lakes System, indexed as
Dimensions, etc. (2) Length, steamer track, outlet of South Channel of St. Clair River to Windmill Point Light House; 18.5 miles.
(3) Lenght (right line), on about longitude 82 45'W.; 26 miles.
(4) Breadth (right line), on about latitude 42 25'N.; 24 miles.
(5) Water Surface of the lake (including Detroit River and St. Clair River); 198 Square miles (U.S.), 292 square miles (Canada).
(6) Entire dranage basin (including Detroit And St. Clair River); 3,05 square miles (U.S.), 4,370 square miles (Canada).
(7) General Description.-Lake St Clair is an expansive shallow basin, with low, marshy shores and a flatly sloping bottom. The lake has a greatest natural depth of 21 feet. St Clair River flows N and enters from the N part of the lake through several channels of a wide delta area. The outflow of the lake is at the SW end through the Detroit River. The Chief importance of the lake is the dredged deep-draft channel that leads across it to connect Detroit River and St. Clair River. No large commercial facilities or harbors are on the lake.
(8) Fluctuations of water level.-The normal elevation of the lake surface varies irregularly from year to year. During the course of each year, the surface is subject to consistent seasonal rise and fall, the lowest stages prevailing during the winter and the highest during the summer.
(9) In addition to the normal seasonal fluctuations, oscillations of irregular amount and duration are also produced by storms. Sudden changes in wind or barometric pressure can cause fluctuations of 1 foot or more that may last several hours. At other times, strong winds of sustained speed and direction drive forward a greater volume of surface water than can be carried off by the lower return currents, thus raising the water level on the lee shore and lowering it on the windward shore. This effect is more pronounced in bays, where the impelled water is concentrated in a small space by converging shores, especially if coupled with a gradually sloping inshore bottom which even further reduces the flow of the lower return currents. This effect is very pronouced in Anchor Bay.
(10) Weather.-Strong winds associated with squall lines or winter storms occasionally whip across Lake St. Clair causing a danger to shipping. One July, a line of thunderstorms generated a 61-knot, 1-minute windspeed recorded by a ship traversing the lake. Peak gusts at Selfridge Air National Guard Base have been clocked in the 60-knot range in spring and late fall, and in the 40 to 50 knot range at other times during the navigation season. Winds over the lakes frequently blow out of the S through W, but numerous local effects come into play on this shallow body of water. At selfridge, northerlies and northwesterlies are also frequent, particularly during the morning hours, while southeasterlies are common during spring and summer afternoons.
(11) While haze, and pollution often often drop visibilties below 7 miles, on 9 to 13 days per month, they seldom fall to less than 0.5 mile. Fog, the principal cause of very poor visibilities, is most likely in autumn and early spring. Visibilities of less than 0.5 mile occur on about 2 to 3 days per month during these periods.
(12) Ice.-Ice froms early on this body of water, usually starting in the shallows of Anchor Bay, along the St. Clair shores, and in the E at Mitchell Bay. Because of prevailing winds and currents, the W side of the lake is the last to become covered and the first to clear. Navigation is usually extremely limited by early December. The broken track through the lake closes quickly, but little rafting or ridging occurs. The head of the Detroit River is relatively ice free for the entire winter, except for minor ice jams. Heaviest ice cover usually occurs in late February or early March. Thawing is rapid and is aided by the winds and currents, which move drifting floes to the head of the Detroit River, where strong river currents move them downstream. The lake is usually open by early April.
(13) Navigation regulations.-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.)
(14) 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.)
(15) 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.)
(16) Charts 14850, 14853, 14851.-The main vessel route across Lake St. Clair is through the dredged channel that leads from the head of the Detroit River NE for about 16 miles to St. Clair Cutoff Channel at the mouth of the St. Clair River. The channel is well marked throughout its length by lights and lighted and unlighted buoys, and at its lower end by a 227 45' lighted range NE of Peche Island. A racon is at the front range light. The front range light is protected by riprap and should not be passsed close aboard, even by vessels of shallow draft. Lake St. Clair Light (42 27.9'N., 82 45.3'W.) 52 feet above water, is shown from a white square tower on a cylindrical base on the NW side of the channel at the slight turn near its midpoint. A radar beacon (Racon) is at the light.
(17) In September-November 1990, the controlling depth was 25 feet (27 feet at midchannel) in the Lake St. Clair ship channel.
(18 - 51 omitted)
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