First in 2000 and again in 2005, 2010 and 2015, San Antonio voters elected to support a one-eighth-cent sales tax to protect land over the environmentally sensitive Recharge and Contributing Zones of the Edwards Aquifer via the Edwards Aquifer Protection Program (EAPP). Most of the properties are protected through conservation easements, legal agreements between the City of San Antonio and local ranch owners that limit development and other activities that may impact the water quality or quantity entering the aquifer. In return for placing a property in a conservation easement, landowners are compensated a portion of the appraised value of the land
In 2008, the EAA joined with the City of San Antonio in an interlocal cooperation agreement to provide geological assessment and easement monitoring in support of the growing program. There are currently more than 150,000 acres of land protected under conservation easements, with several thousand more acres planned in the future. The EAA continues to perform geologic evaluations on the prospective properties and conducts the annual monitoring essential to the integrity of the program.