The nearly seven-mile-long Contrecoeur Channel includes four straight sections, 12,800-foot-long St. Ours Traverse, 5,500-foot-long Petite Traverse, 10,200-foot-long Contrecoeur Course, and Contrecoeur Traverse, which are joined by gentle curves or bends.
The front towers and rear towers used on the three ranges were similar. The front towers consisted of thirty-three-foot-tall, square, wooden, structures, with sloping sides and surmounted by a square lantern room, while the rear towers were square, steel, skeletal structures topped by an enclosed watchroom and a square, wooden lantern room. White slatwork was mounted on the side of the rear tower facing the range line for improved visibility during the day.
The following description of St. Ours Traverse Range was published shortly after the lights were placed in operation to mark the axis of the cut in the improved ship channel known as St. Ours Traverse:
Two range light towers were erected and put in operation on the 27th October, 1903. They show fixed white catoptric lights, visible only in the line of range. They mark the tangent previously marked by day beacons, but 75 feet westward of and parallel to them.
The front tower is a square wooden building, with sloping sides, painted white, surmounted by a square wooden lantern painted white with a red roof. It is 33 feet high from the pier to the ventilator on the lantern.
It stands upon a whitewashed concrete pier 22 feet high, built on the beach, 2580 No 13° 52’ E. from the front day beacon, lately removed.
The light is elevated 50 feet above the summer level of the river, and visible 4 miles.
The back light is elevated 87 feet above the water, and visible 4 miles.
It is shown temporarily from a lantern hoisted on a mast rising 15 feet above the steelwork of a skeleton tower. This tower when completed will consist of an open steel framework, square in plan, with sloping sides, painted brown, surmounted by an enclosed wooden watchroom, capped by a square wooden lantern. The side of the framework facing the channel is rendered more conspicuous as a day beacon by being covered half way down with wooden slatwork. The lantern roof will be painted red, the remainder of the lantern, the watchroom, and the slats, will be white. The height of the tower from its base to the ventilator on the lantern will be 64 feet.
The tower stands 2,700 feet S. 15° 30’ W, from the front light, and 125 feet S. 54° 4’ W. from the front beacon, lately removed.
The two lights in one, bearing S. 15° 30’ W., mark the axis of the improved ship channel from gas buoy 5 M. to Bellmouth curve.
J.B. Laporte was hired as the first keeper of St. Ours Traverse Front Range Light at an annual salary of $125, while Jos. Duchrane received $100 per year to look after the companion rear light.
In 1928, a new front light was built at a new location roughly 2,500 feet south of the original site of the front light. This new structure was described as an aluminum-coloured, square, wooden building with a red roof that displayed the light at a height of forty-three feet above the river. The existing rear tower was relocated to a new site, where it stood 2,700 feet from the front light, but the bearing marked by the range was still 181°. For several years before its relocation, the range had been called Île St. Ours Channel (Île Saint-Ours Course).
The range is known today as Route Île Saint-Ours, and square, skeleton towers are used at both the front and rear location to display fixed green lights.