A Thirst for Growth

For decades, Sierra Vista, Arizona, has pumped groundwater like there's no tomorrow. Now, to save the Southwest's last free-flowing river, the city's leaders must confront an age of limits.

  • 'Wildcat' subdivisions spread out from Sierra Vista. Many of the homes have unmetered private water wells

    Adriel Heisey
  • Birders at Sierra Vista's Environmental Operations Park, where wastewater is purified before it eventually seeps back into the aquifer

    Ed Honda
  • Port Huachuca near Sierra Vista, Arizona

    Diane Sylvain
  • A beaver dam on the San Pedro, where beavers were relocated starting in 1999

    ? Robin Silver
  • Center-pivot irrigation near the San Pedro River. The Nature Conservancy and Fort Huachuca have bought 900 acres of farmland and ended groundwater pumping there

    Adriel Heisey
  • At Fort Huachuca, workers construct a recharge basin that will capture runoff and allow it to percolate back into the San Pedro aquifer

    John Roberts photo, Fort Huachuca Environmental and Natureal Resources Division

Note: a sidebar accompanies this story, focusing tightly on the dewatering of the San Pedro River.


A small oasis of cattail marshes and ponds thrives amid the paved roads and parking lots in this city of strip malls and car dealers. Though bird-watchers slink along its shores, trying to catch a glimpse of a black-necked stilt or American avocet, this marsh is not natural. Its water comes from the toilets, sinks and grease traps of the burgeoning Sunbelt city of Sierra Vista.

This is the Environmental Operations Park, a $7.8 million wastewater recharge project designed to help the city hold onto as much of its precious water as possible. Fifty acres of marshy wetlands take up nitrogen from partially treated sewage. Then, the water is transferred into 30 acres of basins, where it is supposed to settle into an aquifer, replenishing the water that’s been pumped out. The recharge project sinks 1,840 acre-feet of water into the ground each year — enough water to cover 1,840 football fields a foot deep. It is the most visible accomplishment of the Upper San Pedro Partnership, a six-year-old consortium that represents government, environmental and development interests.

The partnership has embraced a very ambitious goal: to balance pumping and recharge, and eventually put more water back into the ground than farmers, businesses and residents take out. If it succeeds, Sierra Vista will be able to do what virtually no other community that relies on groundwater in the arid West has ever done — live sustainably on a limited water supply. In water lingo, it’s called "sustainable yield."

Achieving this would also halt the decline of the Southwest’s last undammed and ungrazed river, the San Pedro, which needs ample groundwater to maintain its surface flows. The San Pedro’s marshy jungles of cattails and bulrushes and its unmatched stands of cottonwoods and willows support 350 to 400 species of birds. Up to 4 million visitors come here every year: Sierra Vista has become an internationally known bird-watching destination. But the city’s excessive groundwater pumping could dry up the river; studies have been sounding a warning for two decades now.

The sewage recharge project is just one of 100 activities the partnership has started to save the San Pedro. Over the past six years, it has raised $46 million to plan and build recharge projects, finance water studies and carry out conservation projects. It has started a "Waterwise" public education program. And it has won friends in the research community and among many public officials.

The partnership is the most effective watershed management group in Arizona and perhaps in the West, says Tom Whitmer, a member of the Partnership Advisory Commission and an Arizona Department of Water Resources official. Mark Anderson, a top-level United States Geological Survey official in Tucson who also sits on the 25-member advisory commission, agrees: "They’re making things happen," he says. "They’re more influential than a lot of organizations at securing money to support science to make management decisions."

Despite the partnership’s work, groundwater pumping is still on the rise in Sierra Vista. Critics, including both local and national environmental organizations as well as neighborhood groups, are growing impatient. The Arizona Department of Water Resources estimates that the overdraft has reached about 8,400 acre-feet annually, a 20 percent increase since the partnership was founded. Holly Richter, a Partnership Advisory Commission member and The Nature Conservancy’s Upper San Pedro program manager, says that when conservation measures are properly accounted for, the overdraft is more like 3,500 acre-feet. But the Audubon Society, another Partnership member, says that number can’t be validated without further study.

There are other questions. The U.S. Geological Survey has found layers of clay and silt 100 to 200 feet thick, 100 feet beneath the wastewater recharge ponds. Clay is far less permeable than sand or gravel, and it could be actually diverting the effluent northward, away from the river. One spring a mile and a half north of the recharge plant seems to be increasing its flow.

The critics say that even if the recharge plan works, it’s no more than a Band-Aid slapped on the San Pedro’s primary threats: growth and unregulated groundwater pumping. So far, the Upper San Pedro Partnership has been unwilling to confront these issues. Partnership leaders say conservation can’t do the job alone, and that growth can’t be stopped, although it can be redirected. They warn that Sierra Vista may eventually need to import water.

In an era of drought, the partnership wants it all: growth, a bustling economy — and a healthy San Pedro River. The question arises: Is that even possible?

Born of failure

The Upper San Pedro Partnership, like so many of the West’s collaborative enterprises, grew out of the muck of past failures and old conflicts. Doubts about Sierra Vista’s water use began to surface in the 1980s, when the first of a long list of studies from state and federal agencies and university scientists warned that the San Pedro River was living on borrowed time. Continued overpumping, they said, was to blame (HCN, 6/12/95: The Southwest's last real river: Will it flow on?).

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