PHOENIX - A key tributary of the threatened San Pedro River will be protected from development and groundwater pumping thanks to the donation of historic Cobra Ranch to The Nature Conservancy in Arizona by Dan Bates, a Tucson artist and restaurateur.

Cobra Ranch includes 1,250 private acres and 10,000 acres of state and U.S. Forest Service grazing leases adjacent to the Conservancy's Aravaipa Canyon Preserve, located about 50 miles northeast of Tucson in Graham County.

"It's a precious jewel," said Bates, who owned the ranch with his mother, Mary, for 25 years. "Not only is this property rich in historical importance, but it contains valuable water in a beautiful area teeming with wildlife."

Cobra Ranch contains Stowe Gulch, a drainage area estimated to contribute nearly half of the groundwater flowing to the headwaters of Aravaipa Creek. The creek empties into the San Pedro River, which flows north into the Gila River and eventually joins the Colorado River - all part of Arizona's Great Rivers system.

Aravaipa Creek also cuts through stunning Aravaipa Canyon, dubbed the "Little Grand Canyon," and shelters the best remaining group of desert fish in Arizona. Two are listed as threatened, the spikedace and Loach minnow. Other wildlife living in Aravaipa Canyon includes more than 200 bird species and desert bighorn sheep.

"Cobra Ranch is a tremendous gift," said Ken Wiley, The Nature Conservancy's director of stewardship in Arizona. "It will allow recovery of 1.1 miles of riparian habitat and create new opportunities for improved grazing and watershed management in what is the richest biological region of the state."

The Nature Conservancy's expanded 9,032-acre Aravaipa Canyon Preserve straddles the canyon east and west of a 19,410-acre Aravaipa Canyon Wilderness and includes additional acreage on the north and south rims.

With the Bates donation of private acreage and public land grazing leases, the preserve now effectively protects about 53,000 acres.

Table Mountain, at 6,150 feet in elevation, overlooks this pristine area that boasts a colorful past. Prehistoric Hohokam, Mogollon and Salado peoples, and later, the Sobaipuri Indians farmed the canyon. The Aravaipa Apaches followed and fought many heated battles with the U.S. cavalry in the 18th century. Both Hispanic and Anglo settlers raised cattle, goats and sheep, and the remains of century-old copper mines are evident.

At Cobra Ranch, Bates raised longhorn cattle and hosted family and friends at the 140-year-old homestead of Burt Dunlap, a well-known Arizona territorial legislator. Bates says he donated the ranch in honor of his mother.

The Nature Conservancy is a leading international, non-profit organization that preserves plants, animals and natural communities representing the diversity of life on Earth by protecting the lands and waters they need to survive.

In Arizona, the conservancy has been actively engaged in saving the state's Last Great Places for more than 40 years.