Searching for Water on the San Pedro

In southern Arizona it’s blazing hot in the middle of summer. But that doesn’t deter hundreds of volunteers from getting up at 5:30 a.m. on a mid-June Saturday, grabbing their water bottles and GPS units, and heading for the river.

Their destination — and mine — is the San Pedro River, which begins in Mexico and runs north into Arizona for 170 miles. As they have done for 16 straight years, volunteers fan out to document where the river has water during the driest time of year.

This is an important river. It’s one of the last free-flowing rivers in Arizona and it supports one of the richest bird migration corridors in North America. It also provides water to growing southern Arizona communities, including Sierra Vista and the U.S. Army’s Fort Huachuca. Heading northeastward, the river passes near historic Tombstone, and then into some of the wildest, most rugged lands in the state.

Sixteen years of mapping has documented that much of the upper river is wet, and most of the middle and lower reaches are dry. On average only 32 percent of the river has surface water at this time of year, before the monsoonal rains come in mid-July.

My group mapped a five-mile section of the middle San Pedro. We were lucky. About a mile and a half into our hike, we found a stream of water, not a lot, but enough to wet our shoes and keep our feet cool. The canopy of huge cottonwood trees and willows funneled a pleasant breeze along the streambed.

Volunteers find a trickle of water along the San Pedro © Tana Kappel/TNC
Volunteers find a trickle of water along the San Pedro © Tana Kappel/TNC

The Conservancy can take credit for this desert oasis on the middle San Pedro. In 2002, the Conservancy purchased a 2,150-acre farm, protected it with conservation easements and stopped using irrigation. Now this section of river usually has water.

Where there is water, there is life. Lots of it.

In the coolness of the morning, we heard a symphony of bird sound — Bell’s vireos, pyrrhuloxia, varied buntings, black phoebes, kingfishers and vermillion flycatchers. Perched high on a cottonwood were two great horned owlets – seemingly unsteady in their flight training. On the river floor were feathers of a snowy egret, great blue heron and grayhawk

Ralph, our knowledgeable naturalist and mapping leader, commented on the profusion of Lucy’s warblers: “There are gobs of ‘em. They must be breeding day and night.”

A large black bear left fresh tracks in the sand, his 7-plus inch long feet at least 2 inches larger than the juvenile bear tracks we saw later. We saw mountain lion and badger tracks, trails of a rattlesnake and box turtle, and a water hole dug by a javelina.

The stream had thousands of tiny native fish – longfin dace — and on the dry parts of the riverbed, it was hard not to step on the hundreds of tiny Woodhouse’s toads. Beavers had gnawed trees and built a dam, but their burrows were exposed due to low water. They may have left for wetter homes.

I’m impressed by the resilience of these creatures – how they adapt in the face of little water and extreme drought. Those bears and mountain lions came from miles around to drink. If this stream dries up, where will these creatures find the water they need?

As I drove home, enriched by the morning trek, two roadrunners raced across the road. Then, like a harbinger of doom in an old western movie, two black vultures (not the more common turkey vultures) feasted on road-kill. Was this a bad omen about the river? Will there be enough water in this river to sustain the wildlife while providing for human needs?

I take heart in the hundreds of volunteers who for 16 years, have come out to map where water flows in the river they care about. What I worry about are those who use water without a care, not knowing how fragile this river is, not knowing that their actions could suck this river dry.

Once dried up, it will be very hard to get our river back. And then what will happen to those bears and beavers?

– Tana Kappel is a marketing specialist and writer for the Arizona chapter of The Nature Conservancy

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