Tucson feeds Santa Cruz River with reclaimed water, sparking rapid dragonfly comeback

For nearly 70 years the Santa Cruz River through Tucson ran mostly dry due to groundwater extraction, drought and urban development. In a collaborative "Response Flows" initiative, the City of Tucson, the U.S. Fish and Wildlife Service and the University of Arizona began discharging 2.8 million gallons of highly treated reclaimed water each day into a downstream reach. Within four months, researchers recorded 37 species of dragonflies and damselflies, a striking indicator of water quality and habitat restoration.

Subsequent observations have reported the arrival of mayflies, caddisflies, birds such as herons and kingfishers, and breeding amphibians, while riparian vegetation is greening. The project illustrates a viable model for desert cities to use wastewater for river revitalization, balancing ecological benefits with careful water-quality monitoring and public outreach. Community use of the revived river is growing, with residents walking, bird-watching and schools using it for outdoor education.