Water resources in the desert southwest

As the old saying goes, there is nothing more precious than water in the desert. The Ancestral Puebloans, Hohokam, and other pre-Columbian cultures knew this and built their civilizations near guaranteed water supplies. When the Spaniards arrived in present-day Arizona, they found that the Tohono O’odham and Piman cultures had settled in prime riverine sites, turning perennial flow through lush riparian ecosystems into irrigation water for productive agriculture. The Spaniards followed suit, building their missions along perennial reaches of the Santa Cruz River, including at one place aptly named “Punta de Agua” (Point of Water) south of Tucson. When the Mormons spread southward from Utah in the 1870s, their destinations were riverside settings on the Little Colorado, Salt, and San Pedro Rivers (Figure 4.1).