In 1964, Canada and the United States (U.S.) ratified the Columbia River Treaty (Treaty), a transboundary water management agreement.

The impetus for the Treaty was the disastrous flood of 1948 which devastated the City of Vanport in Oregon and cost many lives, along with growing power demand in the Pacific Northwest. In exchange for providing flood control and for an equal share of the incremental U.S. downstream power benefits, Canada agreed to build three dams – Duncan, Hugh L. Keenleyside and Mica – in British Columbia and allowed the U.S. to build a fourth dam, the Libby Dam, that flooded into Canada.

The Canadian facilities vastly reduced flood risk in B.C. and the U.S The Treaty also enabled the construction of hydroelectric projects in B.C. that provide approximately half of the potential generation in the province, as well as providing for the production of significantly more electricity at U.S. hydropower facilities.

The Canada-British Columbia Agreement (1963) allocated most Treaty rights, benefits and obligations to the Province. Although this agreement retains Canada’s constitutional jurisdiction for international treaties, it requires Canada to obtain the concurrence of the Province before terminating or amending the Treaty

The U.S. prepaid Canada $64 million for 60 years to provide assured flood control operations which resulted in reduced flood damage and increased safety for U.S. citizens. The U.S. also committed in the Treaty to paying Canada half of the incremental power potential that could be produced because of the new flow regimes made possible by the Treaty coordination.

The Treaty dams and reservoirs inundated 110,000 hectares (270,000 acres) of Canadian ecosystems, displaced more than two thousand residents as well as First Nations, communities and infrastructure, and impacted farms, tourism and forestry activities. First Nations and public consultation and mitigation at the time could be considered inadequate to non-existent by today’s standards, and feelings of hurt remain to this day.

The Treaty has no end date but either country can unilaterally terminate the Treaty from September 2024 onwards provided that at least 10 years notice is given.

This ability to terminate the Treaty, and the changing flood control provisions that will occur post-2024 whether the Treaty is terminated or not, prompted both countries to undertake a review of the Treaty to determine its future.


The Columbia River Treaty is an internationally respected water management agreement between Canada and the United States. Although the Columbia River Treaty was ratified in 1964, discussions around the need for transboundary collaboration to address flooding concerns and growing demands for energy began in the 1940s.

Hydroelectric Development on the Columbia River

Hydroelectric development of the Columbia River in the United States began with the construction of Rock Island Dam, completed in 1932. A year later, the United States government, through the United States Army Corps of Engineers began construction of Bonneville Dam, followed by Grand Coulee Dam in 1934. Bonneville Dam and Lock primarily provided power generation and enhanced navigation. Grand Coulee Dam was initially designed for irrigation and power, and later provided additional flood control. While these dam projects provided economic benefits and increased employment during the Great Depression, the dams also blocked salmon and other fish passage up the Columbia River.

When the Grand Coulee hydroelectric plant came into service in 1942, there was little demand for the power. The huge potential for additional power development on the Columbia River, however, soon attracted World War II industries. In addition, the economy and population of the Pacific Northwest grew rapidly during the postwar period. This brought about construction of a number of American dams, both Federal and non-Federal, on the Columbia River main stem and on its many tributaries. These projects, however, provided little reservoir storage to minimize flood risk. As a result, a coordinated plan was developed by Canada and the United States to address flooding concerns, and growing demands for energy within the Columbia River basin on both sides of the border.

International Joint Commission Studies, 1944-1959

In 1944, Canada and the United States asked the International Joint Commission (Commission), an organization formed by both countries under the 1909 Boundary Waters Treaty, to investigate and report on the feasibility of cooperative development of the Columbia River system. The Commission established the International Columbia River Engineering Board whose mandate was to support the investigation and conduct technical studies.

Detailed studies began after a 1948 flood devastated communities along the Columbia River, killing several dozen people, and making thousands homeless.

In addition to the technical studies, the Commission recommended principles for determining and sharing benefits from the cooperative development of the Columbia River system. In developing the principles, the Commission recognized that the construction and operation of Canadian reservoir storage would help regulate water flows on both sides of the border. This would also allow a greater amount of useable energy and a higher level of dependable capacity to be generated at American power plants than was possible without Canadian reservoir storage. This would ultimately enable the United States to serve greater power demands. At the same time, the regulation of reservoir levels would greatly reduce peak river flows during the spring run-off (snow melt) months and provide significant flood protection to Columbia River basin residents in Canada and the United States.

At the same time, the United States Army Corps of Engineers updated its master resource plan which had been the basis for United States’ Federal projects on the Columbia River. Studies in both countries recommended the development of upriver storage on the Columbia River and its tributaries for the economic and flood benefit of both Canada and the United States.

Treaty Negotiations

On February 11, 1960, negotiations began between Canadian and United States representatives regarding the site selection, dam construction and joint use of specific projects. Talks proceeded rapidly. On January 17, 1961, Canadian Prime Minister John Diefenbaker and United States President Dwight Eisenhower signed the Columbia River Treaty.

The Treaty required Canada to provide 15.5 million acre-feet of water storage by building three dams: Duncan, Arrow (later renamed Hugh Keenleyside) and Mica. The Columbia River Treaty also allowed the United States the option to build Libby Dam in Montana. In exchange for providing and operating the Columbia River Treaty water storage projects, Canada received an upfront payment of $64 million for 60 years (to 2024) of future flood control benefits (Assured Annual Flood Control) in the United States.

Canada also received an entitlement to one-half of the estimated additional hydroelectric generation capability at power plants on the Columbia River in the United States that resulted directly from the operation of Columbia River Treaty dams in Canada (the Canadian Entitlement). British Columbia later sold the first 30 years of the Canadian Entitlement to a consortium of utilities in the United States for $254 million, and used the money to finance the construction of the three Columbia River Treaty dams in the province.

Initially, there was disagreement between Canada and British Columbia related to the details of the Columbia River Treaty, including dam site locations. To enable the Columbia River Treaty to go ahead, and in recognition of the costs of developing the dams, the Canadian government and British Columbia signed an agreement in 1963 addressing the issues of authority, benefits and responsibility (Canada-British Columbia Agreement).

On September 16, 1964, United States President Lyndon Johnson, Canadian Prime Minister Lester Pearson and British Columbia Premier W.A.C. Bennett met at the International Boundary at Blaine, Washington and Surrey, British Columbia, to ratify the Columbia River Treaty and its Protocol, which amplified and clarified certain Columbia River Treaty terms. For nearly 50 years, the Columbia River Treaty has been implemented in the spirit of transboundary collaboration that remains true to the origins and vision of the Treaty.

Diverging opinions

In Canada, the years between the Columbia River Treaty signing in 1961 and its ratification in 1964 were characterised with disagreement not only between Canada and British Columbia, but also within the Canadian Columbia River basin.

By today’s standards, there was a lack of consultation with the Columbia River basin residents and First Nations when the Columbia River Treaty was negotiated in the early 1960s. There was also much debate in British Columbia regarding the location of the dams and the desirability of the Columbia River Treaty itself. The International Joint Commission’s International Columbia River Engineering Board studied a number of different configurations for dam construction, each of which resulted in different valleys being flooded.

Debate centred on the tradeoffs between flooding the East Kootenay between Luxor and the International border or flooding the Arrow Lakes. Regional interests generally preferred the Conservation Plan, which limited the flooding in the Arrow Lakes valley to the existing high-water levels, although that option did not provide the 15.5 million acre feet of storage deemed necessary to appropriately limit flooding downstream in the United States.

In September 1961, a series of Water Storage License hearings were held by the Canadian government throughout the region that would be impacted by the flooding. These hearings were, however, limited to water licence issues instead of discussing the Columbia River Treaty itself. In the spring of 1964, a Federal public hearing on the Columbia River Treaty and Protocol was held in Ottawa by the Standing Committee on External Affairs. The Standing Committee’s role was to either accept or reject the Columbia River Treaty and Protocol after hearing from the public hearing interveners, and no changes to the Treaty (already signed by the Canadian Prime Minister and the United States President, and ratified by the United States Senate) were to be considered.

Additional debate surrounded the flooding caused by the filling of the four Columbia River Treaty reservoirs created by the Duncan, Arrow (now named Hugh Keenleyside), Mica and Libby dams. In particular, the filling of both the Arrow Lakes and Koocanusa (behind Libby Dam) reservoirs flooded large sections of valley bottom land. Flooding inundated traditional First Nations’ sites and artefacts, took productive agricultural and forestry areas out of the local economy, displaced communities, and impacted fish and wildlife habitat.

Since the early 1990s, British Columbia has taken a number of steps to recognize the long term impacts in the region most directly affected by the creation of the Columbia River Treaty dams. These steps include establishing Columbia Basin Trust and ongoing conservation and enhancement projects through the Fish and Wildlife Compensation Program.

In contrast to Canada, there was much less controversy in the United States regarding the Columbia River Treaty. Post-ratification discussions were largely confined to whether the United States had agreed to pay too much for the downstream power benefits.

History Fact sheet
Columbia River Treaty
Canada-B.C. Agreement 
1964 Columbia River Treaty and Protocol: A Presentation