Management and Protection of the San Antonio Segment of the Balcones Fault Zone Edwards Aquifer - South Central Texas, USA

In central Texas, the San Antonio Segment of the Balcones Fault Zone Edwards Aquifer serves as the primary source of water for over 1.7 million people. Cretaceous-age Edwards Group limestone and laterally equivalent formations contain the karstified Edwards Aquifer within parts of nine Texas counties. Approximately 8,900 square miles overly the aquifer system. Recharge, water table, and freshwater artesian areas of the aquifer system extend approximately 180 miles east-west and five to 40 miles north-south. Agricultural, industrial, and municipal pumpers, recreational interests, and federally listed species depend on the aquifer as a water supply. San Antonio, the eighth largest city in the United States, obtains over 90 percent of its water supply from the aquifer.

In 1993, the Texas Legislature created a regional groundwater management agency, the Edwards Aquifer Authority (EAA), to “manage, conserve, preserve, and protect the aquifer.” EAA has promulgated regulatory programs to manage aquifer withdrawals and to address certain activities with potential to impact aquifer water quality. Numerous other non-regulatory programs have been implemented by the EAA to fulfill its mission. Most non-regulatory programs are conducted in cooperation with various federal, state, and local agencies.

Aquifer withdrawal management challenges are related to changing trends in water use and a municipally focused water market. Water quality management challenges are primarily related to non-point source activities. Non-regulatory programs include a wide range of research initiatives including aquifer flow path studies, aquifer modeling, and an extensive hydrologic data collection network. A range management program focused on water conservation and participation in an extensive conservation easement program for watershed protection are also functions of the EAA.