South-Central Section - 51st Annual Meeting - 2017

Paper No. 11-5
Presentation Time: 2:55 PM


HAMILTON, Mark and WINTERLE, James, Edwards Aquifer Authority, 900 E. Quincy, San Antonio, TX 78215,

The Edwards Aquifer is a karst aquifer in south-central Texas that provides water to approximately two-million users and springflow for threatened and endangered species at Comal and San Marcos springs. The Edwards Aquifer Authority Act (Act) is the enabling legislation for creation of the Edwards Aquifer Authority (EAA), the agency responsible for managing withdrawals from the Edwards Aquifer. The benefits of managing withdrawals through a permitting system provides sustainability for aquifer users, endangered species, and downstream users. The permitting system is further enhanced by drought management and conservation measures, all enabled by the Act. Combined, these measures result in added certainty to the region by helping to maintain aquifer levels and springflows during times of drought. The benefits attributed to the Act are quantified by forward modeling of projected demand versus actual demand post Act. Pumping trends from 1947 to 1997 show an average annual rate of increase of 6,100 acre-feet/yr2. For the period 1997 (the first year full year of EAA management) to 2014, the annual increase in withdrawal growth ceases. However, during the same 1997 to 2014 period, population in the region increased by approximately 670,000 residents. Comparing projected versus actual pumping for this period, the model indicates approximately 2.6 million acre-feet of water that would have otherwise been withdrawn remained in the system as either stored groundwater or as springflow. The Act is the mechanism that allowed the region to work together in the direction of a more sustainable framework for all users of the Edwards Aquifer.