State budget cuts in 2010 axed a computer-based study that scientists and some activists say would have been critical to understanding how groundwater pumping could affect the San Pedro River near Benson.
The last part of a three-part study would have created a computer model that could determine if groundwater pumping would lower a neighboring underground aquifer, and by extension the nearby San Pedro.
Had the study run on schedule, it probably would have been finished about now, said a federal official — just as controversy is building over effects of a proposed 28,000-home development in Benson.
A large part of the current controversy swirls around the project’s possible impacts on the river. But the prospect for getting the study started again are uncertain at best.
In 2010, this study was killed when the Legislature slashed the state water agency’s budget by 58 percent, triggering a dramatic reduction in the agency’s staffing and forcing closure of its five regional offices, including one in Tucson.
The cuts were needed to balance the budget and focus on core issues such as education and health care at a time of record budget deficits, Gov. Jan Brewer’s spokesman said at the time.
The cancelled computer study would have been financed by the U.S. Geological Survey and the Arizona Department of Water Resources. It was to be one of a three-part effort to study the Benson area’s groundwater resources to examine impacts of future development.
Studies in Mojave County and the Coconino Plateau in Northern Arizona and the Verde River in Central Arizona were also cancelled in 2010, said Tom Whitmer, an ADWR water planning manager at the time.
The first part of the Benson study was published in 2010. The second is likely to be released in the next week or two.
Part 3 of the study would probably have been finished around now if the financing hadn’t been eliminated, said James Leenhouts, director of USGS’s Tucson-based Arizona Water Science Center.
The studies cover an area of the San Pedro Basin from Tombstone on the south to the Redington area on the north, spanning parts of the Upper and Lower San Pedro River.
Such studies are useful because with water issues, “it’s always nicer to stay ahead of the curve,” Whitmer said.
In fact, the three middle San Pedro studies were started jointly by the state and federal agencies in response to the prospect of several big new developments expected at the time, Whitmer said. Those developments never happened due to the real estate bust of 2007-08. But the new Villages at Vigneto project could start selling homes by late 2017 or early 2018.
Its preliminary development plan won Benson City Council approval this week. A final plan will go to the council in 30 to 45 days, an official for developer El Dorado Holdings said.
Activists opposing the project worry that its pumping will dry up the middle and lower San Pedro and kill off many of the big trees that support wildlife. Benson officials say a near-impermeable clay layer between the river and the section of aquifer where pumping would occur would prevent the river from being drawn down — but USGS scientists say clay layers only delay the effects.
“You don’t want to get into a situation where you are playing catch-up with water. The sooner you can get ahead of the curve by using tools like groundwater models, the better off you are going to be able to plan for the future to be able to meet demands for the customer,” said Whitmer.
“The worst call you get at DWR is when you get a caller saying, ‘We’re out of water, what do we do?’” Whitmer added.
But the 2010 budget cuts forced the transfer of the money for studies to other rural water programs, said Whitmer, now natural resources manager for Cottonwood in Yavapai County.
“These are all nice tools to have. Are they essential tools? Well today, some could argue no. But some could argue it at least puts you in a better position,” he said.
A similar groundwater model has been used by all sides of the protracted controversy over management of the upper San Pedro River near Sierra Vista. It has been used not only to show the impact of pumping on that stretch of river, but to help authorities determine the best places for artificial recharge of treated sewage effluent to bolster the river’s flow.
The groundwater model for the Benson area would have enabled officials and researchers to examine effects of whatever people could do to stress the aquifer, be it pumping or recharge, USGS’s Leenhouts said.
“The value of the groundwater model is that it synthesizes all information available to build the model. You could pose questions such as what happens if you pump in a certain area or recharge in another area, and what are the implications of that?” he said.
The Nature Conservancy wrote a report 10 years ago saying that Benson-area groundwater appears to be flowing downstream to the San Pedro near its 2,100-acre Three Links farm property — making the river vulnerable to increased pumping. In all, the conservancy has protected 5,093 acres along the lower San Pedro with outright land-buying and purchases of conservation easements, the conservancy’s Holly Richter said.
But additional data collection and computer modeling would better clarify the connection between groundwater flow, pumping and river flow “under any given scenario,” said Richter, the conservancy’s Arizona conservation director.
“The groundwater provides essential flows for a desert river during dry seasons and drought. But underground aquifers are very complex,” Richter said. “How to manage groundwater in a sustainable manner is not a straightforward question.”
Today, ADWR is non-committal about whether the computer study could still be done. The agency needs three things to justify spending money on such studies: a local partner to provide money or staff time, interest from USGS and some sort of “driver” such as major growth pressures, said Doug Dunham, a special assistant to ADWR’s director.
A similar computer model study conducted a decade ago in the Hassayampa River basin in Central Arizona cost close to $1 million, and this study could cost about the same, Dunham said. The first two studies cost a total of $2.4 million, said Leenhouts.
But in the city of Benson’s current financial state, it’s in no position to spend anything toward a water study, said Brad Hamilton, the city’s engineer and public works director.
“We’re doing furloughs right now. Maybe down the road if the economy picks up, if we get in a better financial position, but right now we’re working four days a week, nine hours a day, and shutting down Fridays,” he said.
