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View: Abstract

The role of transboundary agreements in the Columbia River Basin: An integrated assessment in the context of historic development, climate, and evolving water policy

Hamlet, A.F. 2003. The role of transboundary agreements in the Columbia River Basin: An integrated assessment in the context of historic development, climate, and evolving water policy. pp. 263-289. In H. Diaz and B. Morehouse (eds), Climate, Water, and Transboundary Challenges in the Americas. Dordrecht/Boston/London: Kluwer Press.


The historical development of the Columbia River Basin and its current reservoir operating policies has been strongly influenced by transboundary agreements between Canada and the United States, and particularly by the Columbia River Treaty (CRT) (1964) and adjunct agreements. Following this agreement, a number of major storage dams were built in Canada and the US, and an emphasis on flood control and winter hydropower production became the dominant water resources objectives in the main stem of the Columbia.

The development of the basin for these purposes (and extensive irrigation in some sub-basins) has resulted in pronounced changes in the natural flow regime in the river, and corresponding ecological problems associated with degraded instream habitat that have yet to be resolved. The basin's operating policies are shown to more fully isolate human systems from climate variability than they do other uses of water in the basin, despite federal legislation calling for equal priority between hydropower and fish, and recent efforts to change the operating policies in the face of Endangered Species Act (ESA) listings of salmon and other endangered fish. Vulnerability of the current management system to low-flow conditions, and the conflicting constraints of many existing agreements (among them the CRT), make changes to the basin's operating policies problematic.

Climate change, which is likely to reduce summer water availability due to changes in snowpack and the seasonality of natural streamflows, may exacerbate the existing weaknesses in the Columbia's operating policies and management framework, and is likely to create tensions between Canada and the United States in the context of maintaining summer instream flows. The Canadian snowfields in the basin are largely insulated from temperature-related changes in snowpack for the scenarios examined whereas some areas of the United States are much more strongly affected, particularly in the southern part of the Basin.

The CRT may be both an obstacle and a means to effective adaptation to climate change in the basin. For example, the CRT may add to the United States's vulnerability to summer low-flow conditions by inhibiting what was once natural flow across the border; however, the CRT could also potentially facilitate the transfer of water from Canadian storage in summer via changes in the existing seasonality of hydropower production.