There’s nothing better in a southern Arizona summer than spending a morning on the San Pedro River — the last free-flowing river in Arizona — after a gentle cooling rain. The air is fresh, the dappled leaves of the giant cottonwoods are reflected in the shimmering water. And the birds are warming up for their morning arias. It’s 6:30 a.m. and I and my hiking partners are walking in water.

Which is a good thing. At this time of year, the surrounding desert can hover around 100 degrees. But this morning stays in the 70s. We don’t even break a sweat until around noon.

One hundred years ago, we would have been sweating regardless of temperature. We’re near the once rowdy, historic town of Tombstone. During this town’s heyday, Wyatt Earp and his brothers battled marauding gangs and waged shoot-outs at the OK Corral. Gold miners, trappers, outlaws and cowboys prowled the surrounding desert. They all carried guns and the one thing they all needed was water.

The very water we’re walking in. It’s like a gold vein running through these desert hills. Then and now, it is a life or death commodity – for the wildlife, and for us humans and our growing communities.

That is why we’re here today. We are among more than 100 volunteers, scientists and conservationists who have taken to the river today – in June, the driest time of the year — to find out where there is surface water and where there isn’t. Armed with hand-held GPS units, we are spread out across 170 miles of the San Pedro and its major tributaries. The effort even extends this year south of the border, where mappers covered 30 miles of the river in Mexico.

Why do it? One reason: Because the San Pedro is a river of hemispheric importance — supporting nearly one-half of the bird diversity in North America. It is a flyway and stopover point for millions of birds and butterflies that migrate north from the tropics.

This is the 11th year of the river-mapping effort — and mapping it over time will provide insight into what might be the causes of the San Pedro’s fluctuation in flows — climate change, drought, or groundwater or surface withdrawals.

The San Pedro originates in Sonora, Mexico and flows north through Arizona to its confluence with the Gila River. Along the way, human demands and drought have certainly drawn down the river. Last year, we found that only 36 percent of the San Pedro was “wet” in late June. (This year’s mapping results will soon be posted on

Some people have volunteered many years running, including our team leader for the “Tombstone” stretch, Ted Mouras. He’s a member of Friends of the San Pedro and loves this river — and our trek doesn’t disappoint. Ted, an avid birder, is the first to spot the red flash of a vermilion flycatcher and many of the other birds we see: soaring gray hawks, turkey vultures, summer tanagers and Mexican mallards. Other teams reported seeing great horned owls, Bell’s vireos, and an irritated pair of Harris hawks defending their nest.

The river’s no slouch for other wildlife, either. On a northern stretch of river, along the Conservancy’s San Pedro River Preserve, mappers photographed a large bear track. Other mappers spotted a Mohave rattlesnake, turtles, toads, deer and longfin dace, a native fish. Last year, mappers spotted coatimundi, leopard frogs, bobcat, gray fox, lizards and mountain lion tracks. Even the elusive jaguar has wandered through this region.

All this is why the Conservancy has made the San Pedro a conservation priority, and has worked with local landowners and communities to conserve its precious waters and protect the watershed.

One big success is along the middle San Pedro, where the Conservancy has purchased land, retired the irrigation and returned water to the river. The river and water running through that land — the 3 Links Farm — is bouncing back. There’s even sign of beavers. (The San Pedro was formerly known as Beaver River, before beavers were all trapped out. They were reintroduced here in the 1990s, but many migrated to Mexico.)

Holly Richter, the Conservancy’s Upper San Pedro River project director, rode horseback through some spectacular country on the Babocomari River, a major tributary of the San Pedro. She rode with Mike Hayhurst, a rancher who has lived on the river his whole life.

“He’s seen the pools in the river that have dried up, pools where he used to swim,” says Holly. “He’s sad because he can’t share that with his grandkids. He wants to see this river continue to flow.”

Read more about the committed cadre of San Pedro lovers who come out year after year to walk the river — and how their efforts are helping conservation planners know more about the river’s health.

Tana Kappel is a Tucson-based marketing specialist/writer for the Conservancy’s Marketing Resource Center West. Previously, she was the communications director for The Nature Conservancy in Montana.

(Image: Holly Richter, the Conservancy’s Upper San Pedro River program director, uses a GPS unit to map a stretch of river, her trusty horse Macky provides the transport. Credit: Holly Richter/TNC.)

If you believe in the work we’re doing, please lend a hand.


  1. Though the effort in Mexico has occurred sometimes a few days before or after than in the U.S., there have been river-water-mappers in the stretch 12 miles south of the border since at least 2006.

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