This island has a few private wharves on the west shore of the Chambly basin.

On the west side, a canal separates Demers Island from Lièvres Island; a segment of approximately 240 metres (790 ft) from the Chambly basin serves as a boundary between the town of Chambly and the town of Carignan.

[1] Spring floods often affected the land adjacent to the shores of Demers Island.

At the beginning of the 20th century, Demers Island was designated by the inhabitants of the "Ile au Beurre" sector.

[4] The toponym "Île Demers" was formalized on August 17, 1978 at the Place Names Bank of the Commission de toponymie du Québec.