In Arizona, irrigators are accumulating water credits for water rights they own but do not use because of low crop prices. Institutional changes may mean that farmers can sell these rights to the municipal sector and that as a result, overall water demand may level off or even decline. This could reduce climatic vulnerability. Key points Irrigation is necessary for most crop production in the Southwest, and agriculture is a major water user and holder of water rights. Climatic variations influence water supplies.
High temperatures increase crop water demands.
Land and water are shifting away from agricultural to urban use. Water use varies considerably between cities as a result of urban design and individual behavior. Figure 5.6 shows a dramatic difference in per capita water use between, for example, Santa Fe and Las Vegas. Urban demands also vary seasonally due to climate and other conditions, with the greatest demand in summer months. Urban populations are growing rapidly in the Southwest, at rates greater than three percent per year.