Transboundary Waters

On this page you will find a listing of all the transboundary (those which cross) and boundary (those that form) waters along the Canada-U.S. border with a summary of IJC activities.

The following maps depict the key transboundary basins shared between Canada and the US. Wherever applicable, links to webpages of active IJC boards working in these watersheds are also included. Note that the Health Professionals Advisory Board does not appear under any watersheds because its work is not tied to any one specific watershed.

Yukon - Alaska - British Columbia Region

Icon of the Alaska-Yukon-British Columbia Watershed

The longest river in Yukon and Alaska with a watershed that stretches as far south as British Columbia, the 3,190 km (1,980 mile) long Yukon River is a vital watercourse for indigenous communities, settlers, and industry.

Puget Sound

Icon for the Skagit River Watershed

The Skagit River is a sub-basin of the Puget Sound basin and flows 241 km (150 miles) from British Columbia into Washington state before draining into the north end of Puget Sound. The main basin of Puget Sound runs from the Tacoma Narrows to the waters between Point Wilson and Whidbey Island.

Columbia River

Columbia River Watershed

The Columbia River runs through British Columbia down into the states of Washington and Oregon, but its watershed spreads even beyond that into the boundary states of Idaho and Montana.

St. Mary and Milk Rivers

Icon of the Oldman and Milk Rivers Watershed

The North Milk and Milk Rivers originate in the foothills of the eastern slopes of the Rocky Mountains in Montana and flow northeasterly across the international boundary into Alberta.

Poplar River

Icon of the Poplar River Watershed

Rising in the province of Saskatchewan and flowing 269 km (167 miles) into the state of Montana as a tributary to the Missouri River, the Poplar River has been subject to IJC references and Orders historically, though there are none at the moment.

Souris River

Icon of the Souris River Watershed

The winding Souris River crosses the Canada-US boundary in two places, flowing from Saskatchewan to North Dakota before turning north into Manitoba.

Red River

Icon of the Red River Watershed

Forming the boundary between the states of North Dakota and Minnesota, the Red River flows north into Manitoba before entering Lake Winnipeg.

Lake of the Woods and Rainy River

Icon of the Rainy-Lake of the Woods Watershed

The watershed forms the international boundary between Minnesota and Ontario, where waters flows some 600 km (372 miles) from Great Lakes basin divide, west through the chain lakes to Namakan Lake, Rainy Lake, and the Rainy River through Lake of the Woods, where at Kenora it enters the Lake Winnipeg basin ultimately flowing into Hudson’s Bay.

Great Lakes - St. Lawrence River

Icon map of the Great Lakes and St. Lawrence River

The Great Lakes and St. Lawrence River hold 20 percent of the earth’s fresh surface water or 6 quadrillion gallons, cover a total area of 246,463 square kilometers or 95,160 square miles, and with the St. Lawrence River span 3,700 km (2,342 miles) or almost half of the North American continent.

Lake Champlain - Richelieu River

Icon of the Lake Champlain-Richelieu River Watershed

The long, winding Lake Champlain sits primarily between New York and Vermont, and stretches north into Quebec, where it drains into the Richelieu River – and in turn, the St. Lawrence River.

Lake Memphremagog

Icon of the Lake Memphremagog Watershed

The 1,777 km2 (686 sq mile) Lake Memphremagog is located on the Quebec – Vermont border between Newport, in the United States and Magog, in Canada.

Saint John River

Icon map of the St. John River watershed

The Saint John River rises in separate streams in Maine and Quebec, coming together to form part of the international border between the two nations. It then turns southeastward into New Brunswick, where it flows into the Bay of Fundy.

St. Croix River

Icon of the St. Croix River Watershed

The most easterly transboundary waterway, the 185 km (115 mile) St. Croix River runs along the border of Maine and New Brunswick before emptying into the Passamaquoddy estuary linked through the Bay of Fundy to the Atlantic Ocean.