Range lighthouses were erected on the south side of the River St. Lawrence, near Becancour, to mark the axis of the ship channel, which has been enlarged to 30 feet deep and 450 feet wide, from the lower end of Ile Bigot through Becancour course to Becancour bend; and the old pole lights and beacon which marked the axis of this channel before it was widened, were removed.
The lights shown are fixed white catoptric lights visible 6 miles in the line of range.
The front structure stands on the flats in the River St. Lawrence, off the westerly mouth of Becancour river. It consists of a concrete pier, square in plan, with sloping sides, surmounted by a white hexagonal wooden lantern. The structure is 34 feet in height from the base of the pier to the top of the ventilator on the lantern.
The back tower stands on the mainland, 6,700 feet S. 65° 37’ W. from the front one. It consists of an open frame steel skeleton tower, square in plan, with sloping sides, painted brown, surmounted by an inclosed wooden watchroom and 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 is painted red, the remainder of the lantern, the watchroom, and the slats, are painted white. The height of the tower from its base to the ventilator on the lantern is 63 feet. The tower stands on a concrete pier 10 feet high, square in plan, with sloping sides.
Omar Gingras was hired as the first keeper of the front range light at an annual salary of $150, while A. Tourigny was paid $100 a year to maintain the rear light.
At some point between 1955 and 1994, the characteristic of the range lights was changed from fixed white to fixed green. The present rear tower, a fifty-five-foot-tall, square, skeletal tower, was erected around 2009. The front tower today displays both a fixed green light along the line of range and a fixed green light that is visible from all points of approach. Both towers are equipped with an orange daymark featuring a black vertical stripe.