Arizona has an estimated 600,000,000 acre-feet of brackish groundwater at depths of less than 1,200 feet according to a talk given at last week's joint AIPG - AZ Hydrological Society conference in Flagstaff. Edwin McGavock of Errol L. Montgomery & Associates out of Prescott, described the locations and characteristics of some of the largest brackish water resources as well as costs and barriers to developing them.
[right, Yuma Desalination plant. Credit, Southwest Hydrology]
Two challenges are energy costs for desalination and the disposal of the resulting brine. Apparently, Arizona classifies all aquifers as "Drinking Water Aquifers" including those where the salinity of the waters exceeds that of seawater. McGavock concluded that since "brine injection in deep saline aquifers is often the best, or only, feasible method of brine disposal, the ability to utilize Arizona's abundant brackish groundwater resources may depend on a reappraisal of the aquifer classification system in the state."