Wildman and Forde make my last post on this subject look smart, arguing that the supply-demand imbalance on the Colorado River will hit Arizona and Nevada first:
We find that initial shortages will be borne only by the cities of Arizona and Nevada and farms in Arizona whereas the other Basin states have no incentive to reduce consumptive use. Furthermore, the development of a long-term plan is deferred until greater water scarcity exists.
Wildman, Richard A., Jr. and Noelani A. Forde, 2012. Management of Water Shortage in the Colorado River Basin: Evaluating Current Policy and the Viability of Interstate Water Trading. Journal of the American Water Resources Association (JAWRA) 1-12. DOI: 10.1111/j.1752-1688.2012.00665.x