Is it possible to plan new housing that makes sustainable use of groundwater? Why should we care? One word: California. The members of the Friends of the San Pedro River have concerns that, without our own groundwater use being sustainable, we will follow in California’s footsteps.
While California has historically suffered intermittent water shortages, the past five years of drought have resulted in drying rivers and aquifers, as groundwater was pumped to compensate for the shortfall in the snowpack and surface water. Natural aquifer recharge is typically a very slow process. The water underground accumulated over thousands or millions of years. A sustainable water supply might have been achieved by enhancing recharge to balance withdrawals.
Locally, there are two proposed developments near the San Pedro that would increase groundwater pumping without enhanced recharge to balance the withdrawals. One, the Villages at Vigneto in Benson, is a roughly 12,000-acre development proposed by El Dorado Benson, LLC on private property south of Interstate 10 and just north of Kartchner Caverns State Park accessed from State Route 90. The development would increase the population of Benson significantly from 5,100 residents to as many as 75,000 residents. Nearly 28,000 new homes would be built along with commercial businesses, infrastructure, roads, utilities and amenities. To support this ultimate population, 12,000 acre-feet (AF) would be pumped annually from deep in the regional aquifer. Eventually, such groundwater pumping could deplete the aquifer west of the St. David Cienega in the San Pedro Riparian National Conservation Area (SPRNCA), not to mention the existing communities of Benson and St. David. Aquifer depletion through groundwater pumping eventually could dry up the river near Benson so it no longer supports its rich gallery forest. For communities, aquifer depletion results in prohibitive costs to drill ever deeper wells and, with greater mineral and salt content, severely degrades the water that is withdrawn to make it unsuitable for potable uses without special treatment.
Does the Vigneto plan look sustainable with regard to groundwater resources? No, or at least not yet. The Stormwater Management Plan addresses only flood control and effluent reuse/recharge; it does not propose any enhanced stormwater recharge. The developer has yet to acknowledge that the underground water resource is not limitless. Nor does the Benson City Council — who already approved a development agreement with El Dorado Benson LLC — seem interested in sustainability. For them, there is plenty of water now, so no need to worry. Dollar signs are obscuring their view of the future. But they have the power to require sustainable groundwater use if they wished.
Castle & Cooke Arizona, Inc. plans to build nearly 7,000 homes, Tribute, in Sierra Vista. However, a lawsuit was filed by local property owners and later joined by the Bureau of Land Management, the federal land manager of the SPRNCA. That lawsuit contends that the Arizona Department of Water Resources (ADWR) failed to account for groundwater needed by the river when ADWR issued a certificate of 100-year water adequacy for Pueblo del Sol Water Company to serve prospective residents of the Tribute development. Basin groundwater is a dominant component of surface water and alluvial aquifers under rivers, so pumping under Sierra Vista can impact the river. The judge’s decision in the lawsuit held that ADWR must include the federal reserve water right for the SPRNCA in a re-analysis of the legal availability of water over the next 100 years before concluding that there is adequate water for Tribute. Any appeal in that case will take time to play out.
Efforts to protect the San Pedro River include the San Pedro Conservation and Recharge Network land acquisitions and the Palominas Recharge Facility (85 AF capacity) operated by Cochise County. In the face of the proposed developments, however, it is insufficient. Developers could and should incorporate recharge into their stormwater management plans.
Insisting on sustainability presents funding challenges. We might seek appropriations and grants to help pay for them. It is difficult for cities, counties, the state or federal government to budget for such projects in the current fiscal environment. The developers could be required to contribute funds for recharge facilities as a condition of approval (as they do for roads and flood control). Taxes are an option, but undoubtedly would be unpopular, and require that the public understand the importance of securing our water resources for the future.
The question remains, will we take the long view to balance economic prosperity with sustainable groundwater use? Only time will tell.
Finally, to get an idea of the challenges Arizona faces in managing its water resources, see the program Beyond the Mirage: beyondthemirage.org/. And remember, apathy is ultimately our principal enemy in this battle.