Water, agriculture, and drought in the west under changing climate and policy regimes

Agriculture is the largest water user in the West, and it will play a central role in balancing water supplies with competing water demands in light of climate change. Water resources that are already over allocated face competing demands from growing urban populations, unresolved tribal water claims, and for maintenance of riparian habitats. While many believe we can meet these demands by reallocating water from agriculture, climate change complicates this calculus. Warmer temperatures and longer droughts will reduce regional water supplies and increase agricultural water demands, making transfers more costly. Hydrological-economic modeling studies suggest agricultural water use will decline, leaving urban use relatively unchanged. Although this agriculture-to-urban reallocation of water is often treated primarily as an engineering problem, many legal and institutional barriers exist to large-scale water transfers. Technological fixes to conserve and transfer agricultural water to other uses will likely fail to facilitate climate adaptation unless changes in water management institutions, policies, and economic incentives accompany those technological fixes.