How a Mega-Development Threatens the Last Free-Flowing River in the Southwest

Photograph Source: Katja Schulz – CC BY 2.0

The San Pedro River is the last free-flowing river in the desert Southwest and one of the nation’s environmental crown jewels. It provides crucial habitat for about 45% of the bird species in North America and is home to a rich variety of native wildlife.

Millions of songbirds migrate through this birding mecca every year. The river’s health is critical to the long-term survival and recovery of endangered species, including the yellow-billed cuckoo and the Huachuca water umbel.

But the river is in trouble. According to reports by the U.S. Geologic Survey and the Upper San Pedro Partnership, excessive groundwater pumping has depleted the aquifer that feeds the river, creating a groundwater deficit that leaves the San Pedro River with little or no water to spare.

Now, Scottsdale developers behind a proposed mega-development near the San Pedro want to pump much more — 8,427 acre-feet per year — and they are desperate to deflect attention from the devastating impacts the project would have on the San Pedro.

Groundwater pumping hurts the river

With help from a high-priced Washington, D.C., crisis-management PR firm, they’re fighting to avoid a detailed environmental analysis of their sprawling Villages at Vigneto development.

They know such an analysis would show that the San Pedro is drying up due to excessive groundwater pumping and that Vigneto would be a nail in the coffin for this beloved river, along with the animals and plants that rely on it.

Vigneto’s spokesman Lanny Davis ignores key issues about the impact of this 28,000-home development near Benson in his Sept. 14 homage to development at any cost.  He glosses over the development’s massive groundwater pumping that would feed four golf courses, lakes and fountains in the 12,000-acre faux-Italian village.

Davis fails to mention that the health of the San Pedro depends on groundwater contributions from the aquifer, especially during the driest times of the year. If excessive pumping causes the groundwater level to drop, the aquifer can no longer feed water to the river. The river’s cottonwoods, willows and other native plants will die and the birds and other wildlife will be gone.

Loss of the San Pedro will be particularly disastrous in light of a recent study that found three billion North American birds have vanished since 1970.

‘Adequate water supply’ means little

Davis claims we need not worry because the Arizona Department of Water Resources has certified that Benson will have an “adequate water supply” to support the development. But the agency’s certification does nothing to preserve the San Pedro.

The agency refuses to even consider what groundwater pumping does to nearby rivers.  They claim that it’s not their job and that there is no connection between groundwater and surface water under Arizona law.

Davis also cannot paper over the staggering volume of groundwater pumping with vague statements about how Vigneto’s developer might “assist” with recharge facilities. We need an extensive study on the environmental impacts of the Vigneto development as the law requires.

The massive Vigneto development will pump groundwater from the same aquifer supplying surface water to the San Pedro Riparian National Conservation Area’s St. David Cienega, as demonstrated byisotope-tracer studies and hydrological modeling.

Congress designated the conservation area 30 years ago as rare river habitat deserving special protection. Hydrologists and biologists have determined that sucking up this much groundwater would further lower the water table, reduce water flow and harm the National Conservation Area.

This influence should concern you

Vigneto also offers a disturbing example of political influence at work.

As The Arizona Republic reported, a career U.S. Fish and Wildlife Service official said he was pressured by the Trump administration to reverse his position that a broad environmental review of the development was necessary to protect threatened and endangered species in the area. As a result, federal officials issued a critical permit to Vigneto without looking at the potential environmental harm posed by the entire 12,000-acre development.

U.S. Rep. Raul Grijalva, D-Ariz., is investigating reports that the politically connected Vigneto developer held a “secret meeting” with then-deputy Interior Secretary David Bernhardt shortly before the Fish and Wildlife official reversed his decision on Vigneto.

Everyone in this state who loves the wild outdoors, who cares about our water supply and who wants sustainable communities should be concerned.

Arizonans love our surviving desert wetlands and rivers. We will continue to do everything that we can to protect these spectacular places and the plants and animals they sustain for generations.

Robin Silver, a Flagstaff resident and an emergency room physician, is a co-founder of the Center for Biological Diversity. Reach him at