She knew nothing about science or biology, not a whit about water tables or soil composition, when she and Josiah arrived at El Coronado. "I came from New York. I knew cement!" she exclaims. "You don't even know when it's raining in New York, really. You can't get a taxi—that's it!"

In Arizona, where the yearly average rainfall is only 13.6 inches (compared with 41.9 in New York), water came alive for Valer. It was the fount for every living thing—the leopard frog and the tobosa grass, the bobcat and the hognose snake. There was nothing subtle about the rain here; it came down in sheets during the summer monsoons and then disappeared for months at a time. During one torrential downpour you could get a seventh of your yearly rainfall.

A couple hundred years ago, those storms would replenish the creeks and rivers, seeping into the soil, feeding the grasses and trees, making pools for wildlife. But by the late 1800s, hundreds of thousands of cattle were moved into the borderlands; they ate the grasses down to the ground. Forests were heavily harvested for mining operations. Marshes were drained for farming. Fire, that great regenerator of grasslands and woods, was suppressed. At the end of the 19th century, drought hit the area like a blow to an already rickety body.

Once the land was denuded and sucked dry, rain ceased to replenish. When the monsoons came, water cascaded from the surrounding mountains and hillsides; with no vegetation to slow it down, it flew faster and faster, sweeping away rocks and brush and topsoil with it, scouring the earth, carving ever deeper canyons, ever stonier, until it created a funnel through which it raced, rushing off and away, leaving nothing behind—no rich silt, no woody debris, no water.

After each rain, the land became drier, more desertlike; the soil turned to rock, plants and trees were left high and dry on the rims of canyons, thirsty animals and migrating birds were driven onward...some to extinction in that part of the world.

The first step toward restoring the land was an obvious one. There would be no more overgrazing on El Coronado. Josiah moved the cows around the ranch during the growing season and later to other ranches they bought, allowing them to graze El Coronado only in the winter months. But the next part of the solution occurred by accident. Josiah was looking for a way to keep the water from pouring across a section of the road at El Coronado, so he decided to build a couple of small rock dams, called trincheras. It didn't take long before he noticed that silt was building up at the backside of each trinchera. A while later, grasses were growing there. And then there were puddles that stayed. Murky pools gleaming darkly, long into the dry season.

He and Valer began to think about the mechanism of these little dams. If you could slow down the water, it would no longer cut into the land. The water would linger, dropping silt, and the silt—rich with nutrients—would generate vegetation. Then the vegetation itself would work to temper the water's force.

So the Austins began their experiment. They found a group of men from a village in Central Mexico whose forefathers had been building rock dams for hundreds of years. This crew taught the Austins how it was done. They began way up in the Chiricahua Mountains, working their way down. They also built bigger dams called gabions, which involved putting the rocks in wire cages first and then attaching the cages to each other. Unlike large, water-holding dams that wreak havoc on the ecosystem by turning flowing rivers into placid reservoirs and actually increasing erosion downstream, trincheras and gabions allow the water to continue to flow, only at a slower rate.

"We did thousands of these dams! We stopped counting at 20,000," Valer says. She pauses for a moment, her eyes fixed brightly on mine, to let that fact sink in. "You know like a little ant does something? We just kept on doing it." They planted willows and cottonwoods, though many of these trees came back on their own. They seeded native grass and the grass reseeded itself.

Today, in the middle of an ongoing drought across the Southwest, West Turkey Creek is flowing. Scientists come from all over to study the flora and fauna on El Coronado. A group of researchers from the Rocky Mountain Bird Observatory are staying at the ranch while they count birds. A 20-plus-year study on Sonoran mud turtles is being conducted here. Every spring the Austins host a hummingbird banding project.

While scientists make good use of the Austin ranches for research, they're also close advisers to the couple. It was the late ichthyologist W.L. Minckley who convinced them to reintroduce certain rare and endangered fish to West Turkey Creek, like the Yaqui chub, a small, silvery minnow that had been collected from the creek by a government biologist in 1895 but had since disappeared. Explaining how a New Yorker who never noticed weather became a harvester of rain, Valer says, "I was converted by this little fish."

Walt Anderson, one of the biologists who has worked with the Austins, calls what they did at El Coronado a "remarkable demonstration"—an experiment that could be replicated. "I watched that landscape change from rockland habitat to robin and frog and turtle habitat. They showed it right there that you could convert what looks to be arid landscapes into lush landscapes." In other words, you could bring land back from the dead.