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Controversy at Cienega Creek: Water for Copper Mining and Streamflow?

By Dos Aguas Arizona’s Empire Ranch The Empire Ranch entrance road transports its travelers from 21st century Sonoran Desert—scattered desert scrub, paved highways, speeding traffic, Border Patrol checkpoints, copper mine arguments—into a world of different dimensions. The sun is still bright in a cerulean sky, but the land has quietly opened up—a wide vista, grass waving...

Chiricahua Leopard Frog (Rana chiricahuensis) (Photograph courtesy Jim Rorabaugh, US Fish and Wildlife Service)

By Dos Aguas

Arizona’s Empire Ranch

The Empire Ranch entrance road transports its travelers from 21st century Sonoran Desert—scattered desert scrub, paved highways, speeding traffic, Border Patrol checkpoints, copper mine arguments—into a world of different dimensions. The sun is still bright in a cerulean sky, but the land has quietly opened up—a wide vista, grass waving in the breeze, a few cattle scattered over the rolling hills, and tall trees bunched along the distant stream.

On a warm June morning Randy Serraglio and Dos Aguas drove into the ranch from Tucson to verify the pre-monsoon water conditions in Cienega Creek and Empire Gulch, its tributary. We also came to survey several of the endangered or threatened species that depend on the water in this corridor, including the Chiricahua Leopard Frog and the Gila Chub.

Randy has been with the Center for Biological Diversity for seven years as their southwest conservation advocate. He leads the center’s efforts on the Rosemont mine, and works on other various issues. He is thin, with a small mustache and goatee, wire-framed glasses, and a determined walk. He was dressed that day in jeans, a long-sleeved shirt, hiking shoes, and his trademark—a dark, stiff-brimmed hat.

Empire Gulch

The cottonwood canopy along the far reaches of Upper Cienega Creek is seen first as a splotchy green line curving around the foothills of the Empire Mountains, just above 4000 feet elevation. To the south and east of the creek stretch the dry grasslands of the Sonoita Plain, the heart of the ranch. To the north and west the rocky ground slopes up toward the highest Empire peak, above 5500 feet.

Cienega Valley in Southern Arizona (Photograph courtesy Diane Drobka)
Cienega Valley in Southern Arizona (Photograph courtesy Diane Drobka)

We parked near the ranch house and headed down the hill to Empire Gulch. The corridor is two to three hundred feet wide, spacious and dusty. We turned east, looking for the short segment of this streambed, which has perennial water. At one time this creek had a strong year-round flow. Now sections of the streambed are dry much of the year, and advocates for conservation are worried that any small change that reduces the remaining water could cause this desert oasis to die. The proposed mining project of Rosemont Copper in the Santa Rita Mountains to the west is the most immediate threat.

We finally found the ‘perennial water’—a quiet pool covered mostly with algae. As we approached there was a single plop, the resulting wake expanding across the pool. We stopped at the water’s edge. Another plop. Randy was glued to his field glasses, adjusting the focus to see below the surface. “It’s hard to tell a body from a clump of algae,” he said. Then, “There he is, in the middle! Two eyes and a green nose.”

Gila Chub (Gila intermedia) (Photograph courtesy Scott A. Bonar, USGS Arizona Cooperative Fish and Wildlife Research Unit)
Gila Chub (Gila intermedia) (Photograph courtesy Scott A. Bonar, USGS Arizona Cooperative Fish and Wildlife Research Unit)

Cienega Creek

Next we headed north and east in the truck, crossing first Empire Gulch (by then dry again) and later a dry section of Cienega Creek. The destination was obvious—the eruption of tall and very green cottonwood canopy along the middle section of the creek, about a mile northeast of us. At last we found a trail descending to the creek bed facing Sanford Canyon. As soon as we entered the canopy shade we found ourselves on the edge of a clear pool, two to three feet deep, with steady current. We stood for a few minutes and soon could make out many fish hanging together. Randy examined them carefully with the field glasses, and then identified the adults as Gila Chub.

“The fish seem a bit anti-climatic, after the frog,” Randy said with a smile, and then bent down for a handful of cress, which he ate.

The Hydrology Debate

There are extremely different judgments about the impact of Rosemont’s proposed open pit mine on Cienega Creek. A hydrologic model constructed for Rosemont Copper predicts a reduction in flow for Cienega Creek of .09 cubic feet/second (which is a 10 percent reduction). Analyses conducted by other hydrologists project a greater drawdown in Cienega Valley groundwater, from up to 50 feet to over 500 feet.

Large groundwater drawdowns would dry up Cienega Creek, but no one can validate any of these projections without more data. Jeff Sims, a biologist with the U.S. Bureau of Land Management, said to Dos Aguas, “We don’t have enough data to know how this system will be affected. And there’s not enough money for studies [i.e., a series of test wells]. So there is risk. The decision is who will carry the risk from this uncertainty—the mine, by not pursuing this opportunity, or the environment, by taking the chance of damage to the creek.”

The controversy about this mine is based partly on science and the interpretation of facts, but it also grows out of a philosophical difference. Randy is a watcher of nature and a proponent of limiting humans’ interventions in natural processes. On the other side of the table, Rick Grinnell of the Southern Arizona Business Coalition has said in defense of the Rosemont Project, “Mother Nature has a way of taking care of herself.”

On the drive back Randy said in a subdued tone, “I helped fight this same battle 17 years ago. At that time it was against ASARCO’s plan for a mine.” He was quiet for a time as the truck wobbled and scraped over the washed-out roadbed. “I hope there can be a final resolution this time, rather than postponing it for another decade, or longer.”

Dos Aguas hosts an online journal of water stories. For more stories, click here.

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