Quebec oil and waterAfter WWII Montreal had the largest concentration of oil refineries in Canada with 7 all clustered in Montreal East, There was a lot of smoke and at night the sky was lit up by flaring from a multitude of chimneys alongside huge fields of giant tanks. The refineries were mainly supplied by a pipeline up from Portland Maine. The St Lawrence, unfortunately, had become a running sewer by the 1960's, due to dumping of wastes, industrial, farming and residential. Environmental practices have improved greatly and now the river is quite clean and birds and fish have returned to a large extent. The river is very tricky to navigate with islands, very shallow in places, and ships need a pilot to bring them up to Montreal.