The Sûreté du Québec (SQ) have discovered the body of a 30-year-old man who went missing in Lac St-Louis in Beauharnois.
The search continues for the other boater who last seen Monday.
On Wednesday morning, the SQ announced that Hydro-Québec would be participating in search efforts by closing the gates outside the Beauharnois power generating station to allow divers to search the area.
The pair launched their boat from the Beauharnois marina during Monday afternoon and were expected to return from fishing in the evening, according to friends and family.
When the pair did not return from their trip, the Châteauguay police, firefighters and the Canadian Coast Guard (CCG) were called to perform a search and rescue of the waters along the southwest shore of St. Lawrence River.
A SQ dive team was asked to perform searches in the area on Tuesday morning, but searches were suspended later that night when the sun went down.