Northern Bexar County Groundwater

The Trinity Aquifer started SAWS’ water diversification initiative as the first non-Edwards Aquifer potable water supply in 2002.

The Trinity Aquifer stretches across the Texas Hill Country including Northern Bexar County. The Lower Glen Rose and Cow Creek formations comprise the best producing sections of the Trinity Aquifer.

SAWS has three Trinity Aquifer projects in Northern Bexar County: Texas Water Supply Company, Oliver Ranch, Timberwood Park.

Texas Water Supply Co.

SAWS has an agreement with the Texas Water Supply Co. to purchase water from the Trinity Aquifer. This is the largest Trinity Aquifer project able to produce up to 17,000 AFY*.

Oliver Ranch Project

The Oliver Ranch Project is an agreement with the Massah Development Corporation to purchase water from the Trinity Aquifer. It was the first non-Edwards Aquifer water to enter the SAWS distribution system in early 2002.

Timberwood Project

The Timberwood Project is the smallest producing project delivering up to 2,000 AF of Trinity Aquifer water from 4 wells in Northern Bexar County.

Combined, SAWS received approximately 3,400 AF from these three Trinity Aquifer projects. This accounted for about 1.0% of SAWS’ total distribution in 2023.

trinity map


vista ridge pipes

Vista Ridge Pipeline

The largest non-Edwards Aquifer supply in our city’s history, the Vista Ridge Pipeline secures San Antonio’s water future for generations to come.


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Firm yield – The volume of water which can be produced from a defined source during a repeat of the drought of record under existing regulatory, legal, contractual, hydrological or infrastructure constraints

AFY – 1 acre-foot per year = 325,851 gallons per year