USING BRACKISH WATER FROM KARSTIC AQUIFERS TO AUGMENT FRESHWATER RESOURCES IN THE SEMI-ARID SOUTHWEST

Access to adequate supplies of fresh water is becoming an increasingly critical issue in many parts of the world. In arid and semi-arid regions of the southwestern United States, diminishing water supplies and extended periods of drought have generated an interest in non-traditional water resources, and the development of new technologies such as desalination of brackish water to exploit those resources. New Mexico has limited supplies of fresh water, but has very large reserves of brackish groundwater. However, our knowledge of the quality and volume of these brackish water resources varies significantly across the state.

The Capitan Reef is a Permian-age karstic limestone aquifer that encircles the Delaware Basin in southeastern New Mexico and west Texas. The reef aquifer is the principal source of fresh water for the city of Carlsbad, NM. However, throughout most of its extent water in the reef is a brine, with TDS content >10,000 mg/l. This brackish water resource, apparently useless for human consumption, has significant industrial applications. Both the petroleum industry and potash mining industry have expressed interest in exploiting brackish water resources in the reef aquifer for hydraulic fracturing of oil wells and processing of potash ore. The use of treated Capitan Reef brine for these industrial purposes will reduce the impact of withdrawals on the limited freshwater resources in the region.