St. Lawrence River, Quebec, Ontario, New York
St. Lawrence © Dave Finger

The St. Lawrence River drains the waters of the world's largest freshwater ecosystem, the Great Lakes, traveling 1,197 km before reaching the Atlantic Ocean. The St. Lawrence is historically significant, having sustained the Algonquin and Iroquois peoples who first populated its shores and serving as an important trade route for European colonists. The river is home to river otters, beluga whales and more than 100 species of fish, and provides seasonal habitat for virtually all of the world's snow geese.

Threats: The St. Lawrence has been heavily impacted by numerous dams, locks and canals. It has been diverted and dredged to form the St. Lawrence Seaway, one of the world's busiest shipping corridors.

The Moses-Saunders Dam has reduced the natural variability in water levels by 70 per cent. Flow regulation has dramatically affected wetlands in the watershed, reducing some types of vegetation by as much as 50 per cent and causing a decline in bird species adapted to local wetland ecosystems. At least 20 of the animal and plant species that inhabit the St. Lawrence watershed are listed as vulnerable, threatened or endangered.

Additionally, climate change is expected to reduce flows into the St. Lawrence from Lake Ontario as much as 24 per cent annually by 2050.

St. Lawrence Watershed

View St. Lawrence River Report Card

Red indicates a poor status; flows are substantially altered from the natural regime, and key species and ecosystems that depend on natural flows are significantly affected. The downward arrow indicates a declining forecast.
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View St. Lawrence River Report Card