A reconnaissance study of the potential for large scale irrigation of the Canadian prairies

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McPhail, Gordon D.
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The results of a reconnaissance study into the feasibility and possible extent of large scale development of the irrigation potential of the Canadian Prairies are presented. The study examined the potentially irrigable areas, the expected benefits and costs of the on-farm irrigation development, the costs of the conveyance systems required to develop the proposed projects, and analyzed the overall economic worth of developing the irrigation potential of the prairies. A water balance model of the prairie river network developed to examine the flow allocations required for large scale irrigation of the prairies is also presented. The study identified approximately 4,000,000 hectares of land as potentially irrigable, and examined 41 different irrigation projects. Based on the results of the economic analysis and the flow allocations determined from the water balance model, approximately 2,965,000 hectares could be irrigated for a total cost of $8.2 billion and would produce direct net on-farm benefits having a present worth of approximately $5.6 billion, for a benefit-cost ratio of 0.68. If indirect benefits are included, the total benefits could approach $14 billion. The overall irrigation system comprises 18 discrete projects which have direct benefit-cost ratios ranging from 1.16 to 0.30 at a real effective interest rate of 4.0 percent. The remaining projects were found to have rate of returns of less than 1.0 percent for their direct and indirect benefits under present conditions, and thus were deemed economically infeasible. All of the projects deemed economically feasible by this study were supplied with water from the Saskatchewan-Nelson river basin. Should future conditions require additional irrigation development then inter-basin diversions of water from the Smokey, the Peace, or the Churchill rivers may be required to supply these additional developments. Based on the analysis of the various projects examined, the study concluded that the irrigation potential of the prairies warrants further, more detailed examination than was possible in a study of this nature. In comparison with the potential benefits, the expected cost of such a study would be insignificant.