Reclaimed water revives Tucson river, bringing 37 dragonfly species in just 4 months

damselflyRepresenative image from Canva For much of the 20th century, the Santa Cruz River that winds through Tucson, Arizona, existed more as a memory than a living waterway. Groundwater pumping, drought and urban growth drained the riverbed, leaving long stretches of dry sand and scattered pools. Then, in a quiet but transformative experiment, treated wastewater, reclaimed effluent, began flowing into the river at a rate of 2.8 million gallons a day. Within just four months, scientists recorded 37 species of dragonflies and damselfly returning to the channel, a rapid sign that life could come back when water did. As documented by the U.S. Fish and Wildlife Service and researchers at the University of Arizona, this resurgence is reshaping how cities think about rivers, reuse and restoration in the desert.A river that disappearedThe Santa Cruz River has shaped Tucson’s history for thousands of years, supporting Indigenous communities, Spanish missions and later Anglo settlement. But by the mid-20th century, the river was in trouble. Extensive groundwater pumping for agriculture and a growing city lowered water tables. Droughts reduced natural flows. Upstream diversions and channeli...