About the Edwards Aquifer


  • Physical Address
  • Municipal Plaza Building
    114 W. Commerce, 11th Floor
    San Antonio, TX 78205   
  • Mailing Address
  • P.O. Box 839966
    San Antonio, TX 78283-3966
  • Phone
  • 210.207.2815 or 210.207.2162.
Email Edwards Aquifer Protection Program


  • Grant EllisGrant Ellis Email
    Special Projects Manager
  • Susan CourageSusan Courage Email
    Senior Management Analyst


The Edwards Aquifer provides San Antonio with an abundant source of groundwater vital to the livelihood of a growing population and an expanding economy. It stretches across thousands of acres over several counties in South Central Texas. Roughly 70 percent of the recharge zone is located west of Bexar County. Rainfall enters the aquifer through fractures, caves, sinkholes and other features and replenishes the aquifer. However, rapid growth and development continue to impact the aquifer, reducing the number of recharge features needed to maintain San Antonio's primary water resource. While rules are in place to regulate development and pollution, the best way to protect the aquifer is to conserve the sensitive and irreplaceable land located over its recharge and contributing zones.water hose 

2000 Proposition 3

Voters first approved a 1/8-of-a-cent addition to the local sales tax in 2000 to collect $45 million to purchase sensitive properties located over the Edwards Aquifer. Before this election, there was no program designed to identify and protect sensitive land located over the aquifer. This was a parks and watershed program and, due to restrictions in state legislation, protection efforts under the Proposition 3 program were limited to Bexar County.

The majority of these funds (approximately $38 million) were used to acquire almost 6,500 acres of land. Many of the properties were former ranches and estates characterized by unique natural and man-made features and hilltops with long, scenic views. The properties range in size from 50 to 1,164 acres and are located primarily over north central and northwest Bexar County. Properties will be turned into natural areas for hiking and nature appreciation and will become distinctive pieces of San Antonio's municipal park system. Remaining funds were used for park operations and maintenance and for appropriate improvements designed for recreational and educational purposes.

2005 Proposition 1

In 2005, voters again approved a 1/8-of-a-cent addition to the local sales tax, this time to collect $90 million for the purchase of sensitive properties located over the Edwards Aquifer. Due to changes in the state legislation, funds collected through the 2005 Edwards watershed protection initiative, titled Proposition 1, were used to acquire and preserve the most environmentally-sensitive properties located over the aquifer within Bexar County and beyond county lines.

Careful consideration was given to the selection of appropriate properties for acquisition as part of the Edwards Protection Program. Scientific evaluation teams comprised of geologists, hydrologists, land use planners and other aquifer experts outlined and prioritized undeveloped properties based on their environmental characteristics in order to achieve maximum value for voter-approved dollars. Consideration was also given to parcels located adjacent to one another in an effort to preserve large land masses and natural areas.

Between the Proposition 3 and Proposition 1 programs, over 96,500 acres over the aquifer have been successfully protected. Following acquisition, the environmental characteristics of each of the protected properties are monitored and evaluated on an annual basis to ensure compliance with aquifer protection program guidelines and restrictions.

2010 Proposition 1

In November 2010, voters approved the continuation of the 2005 sales tax (up to $90 million) for the Edwards Aquifer Protection Program. This initiative, also called Proposition One, authorizes the City of San Antonio to continue the watershed protection and preservation projects initiated in 2000 and continued in 2005. The City continues to protect the Edwards Aquifer by acquiring and preserving land across strategic areas of the aquifer's recharge and contributing zones. By working with scientists, conservationists, landowners, and concerned citizens, the City of San Antonio looks forward to building on the success of the past aquifer protection initiatives.