Chapter 10.9 - Case Study: Protection of Edwards Aquifer Springs, the United States

Abstract

In south central Texas, the Edwards Aquifer gives rise to some of the largest and most important springs in the United States. By the 1980s, a number of highly adapted endangered species had been identified that rely on natural artesian spring flows and aquatic habitats just downstream. Even as water resources became increasingly strained by the needs of over 2 million people, there was a growing awareness of the importance of spring flows for both environmental and economic concerns. In addition to endangered species, important regional economies also depend on spring flows, and large commercial fisheries in the coastal bays and estuaries depend on freshwater inflows. The Edwards limestone is between 300 and 700 ft thick, outcrops at the surface in a narrow band below the escarpment, is tilted downward toward the south and east, and is overlain by younger limestone layers and thousands of feet of sediments. Where the Edwards limestone is exposed, over an area of approximately 1250 square miles, the highly faulted and fractured outcrop can accept large quantities of recharge. Water drains toward the recharge zone from the contributing zone, an area of about 5400 square miles that is known both as the Edwards Plateau and the Texas hill country. Managing recharge water quality in the Edwards mainly involves controlling land use, but Texas is a state where politically powerful landowners and developers view environmental controls and restrictions as a seizure of private property. As growth exploded over the recharge and contributing zones around San Antonio, effective rules aimed at maintaining recharge water quality have remained completely inadequate.