Conservation Efforts of the Edwards Aquifer Region
By Ric Jensen
Several innovative programs are being developed to optimize water use throughout the Edwards Aquifer region-the primary source of drinking water for San Antonio and much of the surrounding area.
The Edwards Aquifer covers an area that is 180 miles long and 40 miles wide and stretches from Brackettville in Kinney County to Kyle in Hays County. More than 1.7 million people live in the region and the population is growing rapidly. Urban, agricultural, and industrial users depend on the Edwards as the major freshwater source in the area. The aquifer provides flows to Comal and San Marcos Springs, which are home to threatened and endangered species.
In the upper parts of watersheds, the aquifer is recharged by streams and rivers from which waters percolate into the fractured karst limestone formations. Furthermore down the watershed, rivers and streams in San Antonio, San Marcos and New Braunfels are fed by Edwards spring flows.
The volume of water withdrawn from the Edwards Aquifer has varied over time. Regional pumping reached a peak of 542,000 acre-feet (ac-ft) per year in 1989. Thanks to groundwater management and conservation plans, pumpage for permitted water users averaged roughly 394,000 ac-ft annually over the last decade. The exact amount of water that can be pumped from the aquifer without threatening springflows is dependent on regional rainfall amounts and the resulting recharge.
The Edwards Aquifer is one of the few groundwater systems in Texas where users must obtain a water rights permit to pump. Senate Bill 1477, passed in 1993, required that groundwater rights in the region must be allocated based on historic pumping levels. Municipal and industrial water users were guaranteed rights to the amount of water they historically used from 1972 to 1993. Agricultural users were guaranteed two ac-ft per acre for the largest number of acres they irrigated during that same period. Senate Bill 1477 also allowed the transfer of water rights. Holders of irrigation permits may transfer one ac-ft per acre of their rights, but one ac-ft per acre must be retained on their land for irrigation. Over the years, municipalities throughout the region have leased more than 190,000 ac-ft of groundwater withdrawal rights.
The Edwards Aquifer Authority (EAA) is developing a groundwater management plan required by Senate Bill 1, passed in 1997. The plan encourages efficient groundwater use and conjunctive management of surface and ground waters. The regional water plan developed through the Senate Bill 1 planning process suggests that more efficient water use and conservation will make up 21% of the area’s water supplies by 2050.
Several entities in the region are encouraging water conservation. San Antonio Water System (SAWS) and EAA have developed education and awareness programs to increase water conservation inside and outside the home, and have created rebates to foster use of water-efficient technologies. Through conservation, SAWS has reduced average water consumption from 231 to 132 gallons per person per day. SAWS is working with golf courses to help them develop and implement water conservation and water quality protection programs.
Additionally, water suppliers in the region are considering innovative approaches to develop future water sources for the region. SAWS implemented an aquifer storage and recovery project to store water in a groundwater formation in Bexar County, where water will not be lost to evaporation. This will allow for the reserve storage of more than 3.5 billion gallons of water for later use.
SAWS and other entities are considering plans to import groundwater from Goliad, Refugio, and Victoria Counties as well as working with the Guadalupe-Blanco River Authority to divert water from the region’s rivers to reduce stress on groundwater supplies.
At Texas State University, the Edwards Aquifer Research and Data Center has established a network of groundwater wells throughout the region to monitor changes in water levels and springflows. They are also characterizing the ecology of the Blanco River watershed, and developing education programs for public schools.
Texas Cooperative Extension is encouraging efficient water use in landscapes through the Seasonal Irrigation Program (SIP) and Master Gardeners. SIP provides homeowners with daily advice about the amount of water to apply to specific landscapes from March to October. Master Gardeners provide classes with information about efficient water use and pesticide management practices.
In the Uvalde region, Texas Agricultural Experiment Station and Texas Cooperative Extension professionals are engaged in research and demonstration programs to help agricultural producers use water most efficiently. Efforts, in many cases joint with USDA Natural Resources Conservation Service, involve evaluating use of center pivot and drip irrigation for crops and improved pastures, developing new irrigation strategies to grow crops when water is limited, and eliminating water waste.
