Utah is an arid climate with the average annual precipitation near or below 10 inches in the
western and eastern sides of the state (Figure 4-38Figure 4-38). The majority of the precipitation
falls at higher elevations. The net result is that life in most of Utah has developed either near the
edge of what is possible with existing water supplies or has grown dependent on augmented
water supplies in some fashion.

Aridity should not be confused with drought. Drought describes conditions that are unusually
dry for an unusual length of time, relative to ‘normal.’ However, when normal conditions barely
support life as we know it, drought can have a particularly harsh impact.

Drought has financial costs. Costs can be direct, such as increasing the amount of water that
must be purchased to irrigate crops and livestock. Costs can also be indirect, such as by
increasing the extent of wildfire and exposing people to hazardous levels of smoke. Often, the
indirect costs of drought can be far greater than direct costs.

Trends in drought and precipitation continue to be areas of intense research and general
interest. Concerns range from short term drought conditions to the long-term decline in ‘normal’
precipitation caused by climate change. At the same time, Utah is one of the fastest growing
states in the U.S. This has put strain on local water management and has increased the risk of
drought.

All drought is caused by a deficiency of precipitation over an extended period of time. Defining
what drought means depends largely on one’s perspective. A farmer likely has a very different
view of drought than a fisheries biologist, a reservoir manager or a recreational skier. In addition,
the effects of a lack of precipitation evolve over time. Various definitions of drought have been
developed that are sensitive to these various perspectives.