THE EDWARDS AQUIFER: THE PAST, PRESENT, AND FUTURE OF A VITAL WATER RESOURCE

The Edwards aquifer system is one of the great karstic aquifer systems of the world. It supplies water for over 2 million people and for agricultural, municipal, industrial, and recreational uses. The Edwards Aquifer in the San Antonio area was the first to be designated as sole source aquifer by the EPA in 1975. The Edwards also hosts unique groundwater, cave, and spring ecosystems. Its large springs that discharge along the Balcones Fault zone became the sites for cities of Austin, San Marcos, New Braunfels, San Antonio, and Uvalde. A new GSA memoir reviews the current state of knowledge, current and emerging challenges to wise use of the aquifer system, and some of the technologies that must be adopted to address these challenges. Recent focused studies have led to improved insight on the nature of the aquifer, including its boundaries, (karstic) flow regimes, ecology and endangered species, water chemistry and quality, and the potential effects of urbanization, climate change, and evolving water law/policy. Even with over a century of study of this aquifer system much remains unknown, but research has fostered refined regulations and improved management strategies that rely on more representative and comprehensive conceptual and numerical models. The memoir’s 27 chapters represent the current state of science of the aquifer and provide the foundation where additional study is needed to resolve outstanding uncertainties of this major aquifer system.