How Humans Use the St. Lawrence River: Highway, Power Plant, Playground & Water Tap

The St. Lawrence isn't just a river—it's a 3,058 km (1,900 mi) multi-service corridor binding the Great Lakes to the Atlantic. Five pillars of human use:

1. Commercial Superhighway — The St. Lawrence Seaway

• 15 locks (7 upstream, 8 downstream) lift ships 168 m (550 ft) from Lake Ontario to Montreal
• ~40 M tonnes/yr: grain, iron ore, steel, machinery, project cargo
• Seaway max dimensions: 225.5 m LOA × 23.8 m beam × 8.08 m draft ("Seawaymax")
• Economic impact: ~US$50 B/yr (US + Canada)

2. Hydroelectric Powerhouse

• Robert Moses Niagara (NY) — 2,700 MW
• Beauharnois (QC) — 1,900 MW
• Moses-Saunders (NY/ON) — 1,950 MW (shared)
• Total basin capacity >20,000 MW — backbone of Québec & NY grids

3. World-Class Fishery

• Walleye, smallmouth bass, northern pike, muskellunge, Atlantic salmon (restored), lake sturgeon (recovering)
• Recreational value: ~US$200 M/yr; commercial harvest managed by binational committees

4. Recreation & Tourism Magnet

• Thousand Islands (1,864 islands) — boating, diving, Boldt Castle
• Saguenay Fjord — whale watching (belugas, blues, minkes)
• Kayaking, sailing, cruise ships (Québec City → Great Lakes loops)

5. Drinking Water for Millions

• Montréal, Québec City, Trois-Rivières, Cornwall, and dozens of smaller municipalities
• Intakes monitored for PFAS, microplastics, algal toxins — binational Great Lakes Water Quality Agreement

Governance

Managed by the International Joint Commission (IJC) (1909 Boundary Waters Treaty) — a rare model of binational ecosystem governance.

One river: ships, electrons, fish, fun, and life itself.