A Case Study of the Edwards Aquifer

Nathan PenceExecutive Director – Endangered Species Programs

Edwards Aquifer Authority

Edwards Aquifer

Edwards Aquifer

• Balcones Fault Zone• Limestone and Artesian Aquifer• Aquifer responds directly to pumping or recharge • 4350 square miles• Austin, San Marcos, New Braunfels, San Antonio• Headwaters to San Marcos and Comal Springs

Edwards Aquifer cont.

• Guadalupe River baseflow• Home to Endangered Species

• Comal Springs Dryopid Beetle• Comal Springs Riffle Beetle• Fountain Darter• Peck’s Cave Amphipod• San Marcos Salamander• San Marcos Gambusia• Texas Blind Salamander• Texas Wild Rice

Demands on Edwards Aquifer• Municipal Water• Agriculture Use• Industrial Use• Recreational• Biological • Spring Flow• Pumping vs. Springflow

Pumping vs Springflow

Limitations of the Edwards Aquifer

• 1956 Drought of Record– Comal Springs ceased to flow for 6 months

• Increased demand • San Antonio: population of 2 million• Surrounding communities

• Increased Development / Reduced Recharge• Drought magnifies all

• Endangered Species Act of 1973

Legal Challenges• Sierra Club v USFWS 1991

• Sierra Club alleged that unrestricted withdrawals from the aquifer would cause take of Endangered Species. Courts agreed and established “take” and “jeopardy” flow rates; water supply restrictions

• 2012 Deadline for “Continuous Minimum Springflows” for the species

• Senate Bill 1477 - 1993• Established EAA and set withdrawal limits