The archipelago’s two largest islands, Île Saint-Ignace and Île Dupas, are partially urbanized, and are linked to the mainland by bridges to the north and a ferry to the south. Most of the other islands are used for farming and grazing animals.
Navigating the winding waterways between the islands of the archipelago can be tricky, and several lights have been established over the years to assist mariners.
Just upstream from the archipelago and the City of Sorel-Tracy, the St. Lawrence River narrows into a relatively straight channel that leads to Lavaltrie. In 1906, a pair of range lights was erected on two islands at the western end of the archipelago to mark the channel between Sorel-Tracy and the lights of the Lavaltrie Range.
This new range was known as Île Dupas, where its rear range was built, but its front light was located to the south on the much smaller Île aux Cochons (Pig Island). Île Dupas is named after Pierre Duppas, who, after his arrival in Canada in 1665, became the first Frenchman to settle on the island.
The following description of Île Dupas Range was published to notify mariners of the establishment of the range at the opening of navigation in 1907:
The front lighthouse stands on the south side of Ile aux Cochons, about 100 feet back from the water’s edge, and about one-tenth mile from the southeast end of the island. It is a square wooden building, painted white, surmounted by a square wooden lantern, painted white. The building is 19 feet high from its base to the top of the ventilator on the lantern, and stands on a concrete pier 22 feet high, square in plan, with battered sides. The light is fixed white catoptric, elevated 39 feet above the summer level of the river, and visible six miles in the line of range.Zotique Coucheane was hired as the first keeper of the range lights at an annual salary of $275.
The back tower stands on the western end of Ile du Pads, 1,960 feet from the front lighthouse, and about 900 feet back from the water’s edge in the line of range. It consists of an open steel square framework, with sloping sides, surmounted by an inclosed wooden watch room 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 lantern sides, the watchroom and the slats are painted white. The height of the tower from its base to the top of the ventilator on the lantern is 69 feet. The light is fixed white catoptric, elevated 71 feet above the summer level of the river, and visible six miles in the line of range.
This work was performed by day labour under the Montreal agency; the steel tower was supplied by the government shipyard, at Sorel, at a cost of $268; and the total expenditure on this work, inclusive of the steel tower, was $10,031.67.
In 1950, the characteristic of the range was changed from fixed white to fixed green, the color the lights remain today. The front light is still displayed from a tower mounted atop a concrete pier on Île aux Cochons, while the rear light is now shown from a 20.4-metre-tall, square, skeletal tower.
Keepers: Zotique Coucheane (1907 – 1912), P. Dandonneault (1912 – 1923), R. Valois (1924 – 1931), A. Courchesne (1931 – 1936), P. Courchesne (1936 – at least 1937).