In the early 1900s, a few pairs of range lights were established to guide mariners along a new channel that was dredged between Verchères Point, at Verchères, and Cap St. Michel, near Varennes.
In 1902, the Department of Marine announced that two range towers had been erected, one on Île Bouchard and the other just east of Île Marie:
Two range light towers, known as the Ile Bouchard range, have been erected in the continuation eastward of the new dredged channel between Verchères point and Cap St. Michel. It is not proposed to put lights in operation in these towers at present, but the buildings are now available for use as day beacons.
The front tower, standing on a high cribwork pier off the east extremity of Ile Marie, is a square wooden building with sloping sides, surmounted by a square wooden lantern. The height of the tower, from the pier to the ventilator on the lantern, is 28 feet; the focal plane of the light when established will be 39 feet above the river. The pier and tower are white, and the lantern roof red.
The back tower, erected near the Southeast shore of Ile Bouchard, and distant 8200 feet N. 51° 15’ E. from the front tower, is a square building with sloping sides, consisting of an open steel framework painted brown surmounted by a wooden watch room painted white and topped by a square wooden lantern painted red. The height of the tower from its base to the ventilator on the lantern is 65 feet. The focal plane of the light when established will be 75 feet above the river.
The lights on Ile Bouchard Range were activated on June 18, 1903, with Yvon Laporte taking care of the front light and Alphonse Chicione, Jr. looking after the rear light. Both lights were fixed white catoptric lights, visible for a distance of eight miles in and over a small arc on each side of the range line.
At some point after 1947, the front light was moved from the pier off the eastern extremity of Île Marie to the southern shore of Île Bouchard, roughly in line with the eastern end of Île aux Prunes. Fixed green lights are now shown from modern towers that are separated by 3,066 feet, instead of the original separation of 8,200 feet.