From the National Geographic Voices blog (Sandra Postel):
“I don’t know what I pump and I don’t care – and that’s crazy,” says Paul Schwennesen, a fit, energetic rancher in his late thirties who might outcompete Clint Eastwood for most handsome cowboy.
On his modest-size ranch, the Double Check, located in the lower San Pedro River Valley of southeastern Arizona, Schwennesen raises cows to supply grass-fed beef to farmer’s markets and seventeen restaurants in Phoenix and Tucson, both cities about an hour-and-a-half away. Schwennesen’s ranch abuts one mile of the San Pedro, and, as an irrigator, his pumping of groundwater contributes to the depletion of the river’s base flow, the current that keeps the river wet and connected during the dry season.
In contrast to most irrigators in the West, Schwennesen wants to be made to care how much groundwater he pumps. A decade ago, he took over operations at Double Check from his father, who now raises cattle in the high country near the Arizona-New Mexico border. Schwennesen is a successful rancher and businessman, but cares about the river, too. In his mind, free water is no friend to the river or the long-term health of the community, and he wants to see water better valued.
“I am a free-market devotee,” Schwennesen said. “Markets are the best way to allocate scarce resources. We’d love to see a market established for water.”
Schwennesen is among a new cadre of farmers and ranchers that brings a more holistic, ecological way of thinking to land management.
“Water is the salient variable in these environments,” he said, as we examined one of his experimental fields on a warm, late-May morning. “Anything you can do to alter the water regime is going to have the biggest effect. And the more organic matter we can squeeze back into the soil, the more water.”
It’s a belief backed by science, and it’s at the core of Schwennesen’s mission. “Well managed land can give back more than it consumes,” he added. “That’s the miracle of it.”
I’ve come to the Double Check smack in the middle of the driest time of the year, typically April to June. The much anticipated El Niño of 2015-16 did not deliver the rains most had hoped for. Just a short distance from where we stood talking, the San Pedro’s channel was dry. Historically this portion of the lower river had flowed intermittently, but over time groundwater pumping and prolonged drought have depleted the base flow and dried up the channel, a condition that’s bothersome to Schwennesen.
The San Pedro is the last major undammed river in the American Southwest. Unlike the Colorado River and the Rio Grande, which flow south toward Mexico, the San Pedro originates in Mexico and flows north some160 miles before joining the westward flowing Gila River near the small town of Winkelman.
It is a winding ribbon of green in the desert that offers biological riches far out of proportion to its size. The gallery forests of cottonwoods, willows and mesquite that band both sides of the river provide some of the best remaining habitat for birds and wildlife in the American Southwest.
More than three hundred species of migratory songbirds seek out the San Pedro corridor as they journey between their wintering grounds in Central America and Mexico and their breeding grounds in the United States and Canada. More than fifteen percent of the world’s known population of western yellow-billed cuckoo breeds along the San Pedro. The river system also sustains some eighty species of mammals – one of the richest assemblages of land mammal species found anywhere in the world – as well as more than forty species of reptiles and amphibians.
For such a modest river, its ecological wealth is extraordinary. But irrigated agriculture, copper mining, and in the upper reaches of the valley, urban growth have placed that wealth in jeopardy. Without the ability to reduce groundwater use and keep the river healthy and flowing, the San Pedro’s bounty and beauty will be sacrificed.
That’s where Schwennesen comes in. He has partnered with the Tucson-based Arizona Land and Water Trust and hydrologists at the University of Arizona to see if he can ranch successfully and profitably while cutting his water use by some 20-30 percent. The strategy is to shift to low water-use crops that include a mix of native perennial grasses and an annual rye crop that is seeded directly into the green vegetative cover, avoiding the tillage action that can erode and dehydrate the soil.
With deep and resilient root systems and microbial activity boosting the level of organic matter, the soil should hold water like a sponge, Schwennesen says, reducing the need for irrigation water and helping to replenish the aquifer that feeds the river’s base flow.