The Santa Cruz River: Dewatered, Restored

The Santa Cruz River made Tucson possible. For thousands of years it ran perennially through this valley, shallow and reed-lined, shaded by cottonwood and willow galleries. The Hohokam built their canals from it. Father Kino built his missions along it. The O'odham farmed its floodplain for generations before any of those arrivals.

By nineteen forty, the river was dry.

The dewatering happened gradually through the late nineteenth and early twentieth centuries as the population of the Tucson basin grew and the demand for groundwater rose faster than the aquifer could recharge. Irrigated agriculture upstream, municipal wells downtown, and the general draw of a rapidly growing desert city pulled the water table down below the riverbed. A river that had run for thousands of years went underground and then stopped. The riparian gallery forest of cottonwood and willow that had lined its banks, habitat for hundreds of species, collapsed.

For decades, the dry riverbed ran through the west side of Tucson essentially ignored, a drainage channel and informal dump. Then, in twenty nineteen, the city began routing treated wastewater into the river channel through what became the Santa Cruz River Heritage Project. The water is not pristine. It is municipal effluent. But it flows.

Within years of flows being restored, native species returned. Cottonwoods germinated. Willows spread. Migratory birds began stopping at what was once a barren channel. Today a restored riparian corridor runs for miles along the west side of Tucson, a green ribbon through the brown desert, sustained by water that was once sewage. The river that made this city is running again.