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The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of Edwards Plateau in the U.S. state of Texas, it discharges about 900,000 acre feet of water a year and directly serves about two million people.[1] The Edwards Aquifer is also home to several unique and endangered species.

Contents 1 Geography 2 Economy 3 Ecology 4 See also 5 External links

The aquifer's recharge zone, where surface water enters the aquifer, follows the Balcones Fault line, from Brackettville (roughly along Highway 90), through San Antonio, and north to Austin (roughly along Interstate 35). Its contributing zone, where shed water is transported near the surface to the recharge zone, extends about 40 miles (64 kilometers) north of the recharge zone at the west end, and tapers to end at a point in the east. The artesian zone, where water springs from wells naturally due to the higher elevation of the recharge zone, extends 10–20 miles (16–32 kilometers) south on the west end to only a few miles south on the east end. Across the eastern half of the aquifer, the recharge and artesian zones occupy common area.

The plentiful water provided by rivers fed from the Edwards Aquifer is the primary reason Spanish missionaries were able to establish so many missions, like the Alamo Mission in San Antonio. Later, immigrants found the Texas Hill Country welcoming because of the food, energy, and water provided by these rivers. Without this supply in the arid plateau, early colonization would have been far more difficult. Cities like San Antonio, New Braunfels, and San Marcos have been able to support large populations without the need to develop surface water resources. Farmers and ranchers south of the aquifer benefit greatly or entirely from the irrigation possible from these rivers.

The Edwards Aquifer is home to several unique species, like the Texas Blind Salamander, Helotes mold beetle, the Robber Baron Cave harvestman, and the Robber Baron Cave spider. These species actually live in the caves, and are either completely without eyes or their eyes are so underdeveloped that they are essentially eyeless. The springs fed from the aquifer are also home to many unique species, such as the Fountain Darter, San Marcos Gambusia (which might already be extinct), and the San Marcos salamander. Texas Wild Rice is also found only in the upper San Marcos River.

• Edwards Plateau
• Balcones Fault
• San Marcos River
• Comal River
• Guadalupe River
• Central Texas
• Texas Hill Country

• Handbook of Texas Online, s.v. "EDWARDS UNDERGROUND WATER DISTRICT,"
• Edwards Aquifer Home Page, Gregg Eckhardt
• Endangered Species of the Edwards Aquifer
• Save Our Springs Alliance - Edwards Aquifer Protection Plan
• Greater Edwards Aquifer Alliance

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