Huge housing plan could deplete San Pedro

San Pedro River in Benson
San Pedro River in Benson

A massive new housing development proposed in Benson could empty the San Pedro River Valley aquifer, impacting agriculture, ranches and wildlife from Mexico to Winkelman.

The builder, El Dorado Housing Inc., plans to build a Tuscan-style complex of 28,000 homes over 12,324 acres along the San Pedro River. Complete with an 18-hole golf course, parks, recreation center and nature trails, the development looks to reinvent the desert community.

The project would more than double the rate at which the town pumps its water now.

Often times, if water is drawn out of aquifers too quickly, there will be little time for the pool to recharge and other water sources in the area, such as the San Pedro River, will run dry as well.

“The planned pumping will significantly increase the rate of depletion of the deeper aquifer beneath Benson and potentially other locations along the San Pedro River as well, with negative impacts to both municipal and agricultural wells,” explained Norm Meader, co-president of the Cascabel Conservation Association in a letter to the Benson City Council.

In a recent lecture at the Benson City Hall, Jim Leenhouts, a hydrologist for the U.S Geological Survey, helped explain aquifers and their importance to the land.

“One way to look at an aquifer is as a storage mechanism, like a bank account,” Leenhouts said. “The recharge to the aquifer, that’s what’s coming in from the rivers, is like your income. The withdrawals you take out, either from wells you pump or natural ground water flowing out of the basin, are all expenditures of your bank account. You don’t want your bank account going to zero.”

If the Villages are built with the proposed water pumping permissions, residents downstream believe it could have devastating results.

The Upper San Pedro Basin contains 19.2 billion gallons. The project wants to pump an additional 3.9 billion gallon a year on top of the estimated 7.1 billion gallons that Benson already uses. That would be 11 billion gallons. Each year, about 5.2 billion gallons recharge the storage from seasonal rains.

In the worst-case scenario, the aquifer could have no available water in five years.

If that happens, environmental activists predict problems for the sensitive area, particularly downstream.  “Nearly two-thirds of all North American bird species nest along the San Pedro during migration,” according to University of Arizona Water Resources professor Mark Apel.

Running 140 miles from south to north, the San Pedro River provides a fertile oasis in the dry sea of the Sonoran Desert. Hundreds of species inhabit the area, including several on the Endangered Species List.

Earthjustice, an environmental law group based in San Francisco, along with the Tucson Audubon Society, Maricopa Audubon Society, Sierra Club, Cascabel Conservation Association, Lower San Pedro Watershed Alliance announced in early March they would sue to delay the plan until the water issue is resolved.

“This is a bigger development than the ones we’ve dealt with in the past so it has the potential for much greater impacts on stream flows,” said Chris Eaton, an associate attorney for Earthjustice. “If steps are not taken to protect the river from excessive human water use and ground pumping, we are going to lose a really impressive ecosystem.”

Matt Clark, conservation analyst with Tucson Audubon Society, echoes Eaton’s comments.

“If we are going to have development, then it needs to be done very cautiously and carefully, especially in proximity to the San Pedro River since it’s a very sensitive area,” says Clark. “This is a globally important area for birds and wildlife. If we treat the San Pedro River like we treated the Santa Cruz River, then there’s going to be a sad ending to this story.”

Jordan Glenn is a reporter for Arizona Sonora News, a service provided by the School of Journalism at the University of Arizona. Reach him at

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