Drought is a recurring—and likely increasing—challenge to water rights administration in western states under the prior appropriation doctrine, where “first in time” senior rights are often allocated to non-survival uses such as commercial agriculture, rather than to drinking water supply for cities. While states and localities facing severe drought have used a variety of voluntary programs to reallocate water, these programs by their very nature cannot guarantee that water will in fact be redistributed to the uses that best promote public health and community survival. In addition, pure market solutions run the risk that “survival water” will become too expensive to buy because prices naturally rise—sometimes dramatically—during shortages....