Abstract

Western water allocation has long been based on the legal principal of prior appropriation, under which the first user to put water to a beneficial use establishes a claim on the use of that water so long as the beneficial use continues. It has historically been difficult, for legal, political, and hydrologic reasons, to subsequently provide for changes in place or nature of the use of water once appropriated. At the same time, the impacts on junior rights-holders and new uses have been compounded by climate variability and growth in demand for the resource.

This article traces the interaction of public policy objectives with the hydrology and ecosystem of the Snake River Basin, the success and growth of irrigated agriculture in the Basin, and, after 1950, with institutional reflections of changing preferences for use of the water.