Water quality in Montréal's streams and ponds

The island's hidden waterways

Montréal still has some thirty streams and inland water bodies: Bertrand creek and Rivière à l'Orme in the west, the De Montigny and Pinel creeks in the east, the Lachine Canal, the ponds of La Fontaine and Angrignon parks, the marshes of the nature parks. The RUISSO programme samples them seven to nine times between May and October.

Faecal coliforms reveal faulty sewer connections and urban runoff. Dissolved oxygen says whether aquatic life can breathe: the Québec environment ministry's criterion is 5 mg/l in warm water. Total phosphorus feeds algae; above 30 µg/l a stream is considered exposed to eutrophication.

How to read this page

The overview aggregates every point of a sampling round; the chips follow a whole stream (mean of its points) and the Specific point menu a single sampling point. Coliforms, phosphorus, suspended solids and nitrogen are drawn on a logarithmic axis, as they vary a thousandfold with the rain.