or Delayed Disaster?

Bruce Thomson

Nabil Shafike

John Hawley

Abstract

           Increased demand for public water supply in arid parts of the U.S. has resulted in willingness by communities to pay more for their water, as well as to search for new sources of water to supplement existing supplies.  New sources of supply include treated wastewater, saline and brackish ground water, and water produced from oil and gas or mineral extraction.  In New Mexico, brackish water reserves are not well characterized, but are estimated to contain up to 1 B acre-ft of water with TDS concentrations greater than 1,000 mg/L.  Several large communities in the state are developing projects to utilize these resources.  However, a fundamental question that has not been fully considered is, are these supplies sustainable?

            This paper will consider issues of sustainability in the context of a proposed brackish water development project to extract 25,000 acre-ft/yr of water from the Estancia Basin, desalinate it, and pipe it out of the basin to the City of Santa Fe.  Geologic and hydrologic evidence suggest that the regional recharge rates are not sufficient to replenish the aquifer at this rate, so that the project lifetime would be about 40 years.  The paper will use the Estancia Basin brackish water development project as a case study to describe the types of investigations needed to consider whether a brackish source is sustainable, the impacts these withdrawals might have on local water resources, and the expected growth and water demands a community might have in 40 years.  The discussion will be presented in the context of similarities and contrasts to a community’s dependence on another extractive resource, electrical energy produced from fossil fuels.