San Pedro River
San Pedro River southeast of Phoenix © Harold E. Malde

Stories in Arizona

San Pedro River: 17 Years and Hundreds of Volunteers

Mapping water in the San Pedro is a labor of love.

Citizen Scientists

More than 100 volunteers have worked along 300 miles of the San Pedro River and its key tributaries to map where the river has water and where it doesn’t.

The “citizen scientists” are equipped with GPS technology, cameras and plenty of water. They are rewarded with wildlife sightings and scenic river stretches. For many, it is an annual event and a labor of love for a threatened desert river that is almost unmatched on the continent for its importance to migratory birds and wildlife.

Group Effort

Dozens of partners coordinate this massive effort that covers more than 300 miles of main stem and tributaries within the San Pedro River Basin. Partners include: The Nature Conservancy, Bureau of Land Management, National Park Service, Arizona Game and Fish, Community Watershed Alliance of Benson, Cascabel volunteers, and Mexican partners and landowners among others, and many local volunteers.

The effort, now in its eighteenth year, extended from San Pedro River headwater streams in Mexico to its confluence with the Gila River near Winkelman, tributaries of the San Pedro including the Babocomari River, Aravaipa Creek, Hot Springs Canyon and many other smaller tributaries.

Water Snapshot

Annual mapping of where there is surface water – conducted during the hottest part of the year – helps determine over the long-term where to focus conservation projects. It provides a snapshot of conditions along the entire river at the same date each year, allowing comparisons of year-to-year variability. In 2016, 38 percent of the river had surface water.

Maps of past wet-dry mapping are available at

As we move into the 18th year of determining where water is present on the river, science shows that our conservation actions are having a positive impact. The mapping information, along with USGS research, has helped the Conservancy, Cochise County, Cities of Sierra Vista and Bisbee, and the Hereford Natural Resources Conservation District, with input from Fort Huachuca, design an innovative regional recharge effort designed to collect local water sources and put it back in the ground, replenishing the aquifer that supports river flows.