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This paper investigates the long-term impacts Of water storage infrastructure (dams) on agriculture and the natural environment in the semi-arid U.S. West. We conduct an empirical analysis of the agricultural impacts associated with major dams in Idaho, focusing on their crop mixes, crop productivities, and overall agricultural land values using an integrated county-level repeated cross section dataset Our results suggest that the presence of a dam resulted in significant increases in total crop acreage, particularly in those counties in which farmers have predominantly junior water rights. Dams led to an increase in the acreage of the higher-valued, more waterintensive crops and positively impacted some crop productivities, particularly during periods of severe droughts. In contrast to the traditional literature, we find that the presence of a dam had a small, positive, but nonsignificant effect on farmland values. Finally, we evaluate long-term patterns in stream flow change and examine the impacts of dams on the natural environment. We find that the presence of dams enabled the spatiotemporal transfer of water resources from cold (non-agricultural) to warm (agriculturally-intensive) seasons, reduced the potential availability of water resources for ecosystem use, and increased the seasonal volatility in water supplies. (C) 2014 Elsevier B.V. All rights reserved.