a riverbed surrounded by greenery
The San Pedro River is a mecca for millions of migrating birds and resident wildlife. © Tana Kappel/TNC

Stories in Arizona

Returning Water to the San Pedro River

Innovative projects are helping to increase the flow of water in one of the longest undammed rivers in the Southwest.

After dropping for decades, groundwater levels in some areas along the upper San Pedro River are rising. The reason: An innovative series of water replenishment projects capable of increasing flows in one of southern Arizona’s last flowing rivers.

The Nature Conservancy and its partners in the Cochise Conservation and Recharge Network seem to have found a formula that works for the river and surrounding local communities.

Returning 2 Billion Gallons to the San Pedro

The regional network of projects encompasses 6,344 acres of lands along about 25 miles of the upper river running through the San Pedro Riparian National Conservation Area. The Conservancy assisted with the acquisition of much of these lands with funding from the U.S. Army’s Compatible Use Buffer Program. Cochise County, the Hereford Natural Resource Conservation District and the City of Sierra Vista supported the design and construction of the projects.

The network projects help the river in two ways. First, the lands are protected from future groundwater pumping, avoiding an estimated 1 billion gallons per year of groundwater pumping that used to occur.  Second, three projects now in operation are capturing about 1 billion gallons of stormwater and effluent and putting it back into the underground aquifer each year. That’s 2 billion gallons of groundwater a year.

a water detention basin
The Detention Basin Constructed in 2014, the Palominas Recharge facility captures stormwater and funnels it underground where it replenishes the aquifer feeding the San Pedro River. © Holly Richter/TNC

Mapping Water Levels and Managing Stormwater

The San Pedro mapping effort the Conservancy coordinates every year has helped determine where the recharge facilities could be most effective.

Additional stormwater and effluent recharge projects are being planned, including a first-of-its-kind facility to recharge excess water flooding off the City of Sierra Vista’s streets, sidewalks and other hard surfaces. 

“These San Pedro projects are unique in their focus of supporting both rural communities and one of the last large desert rivers,” said Holly Richter, water projects director for The Nature Conservancy. “The benefits to the groundwater will be as important for water users on wells, as it will be for the river.”    

closeup of a medium-sized brown furry animal

The San Pedro River

The San Pedro River, one of two Arizona rivers that flow north from Mexico into Arizona, is a hot spot for migrating birds and provides habitat for unique wildlife of the northern Mexico and southern Arizona region including jaguar, coatimundi, gray hawk and ringtailed cat. The San Pedro is a tributary of the Gila River, and both are within the Colorado River Basin