Northern Bexar County Groundwater

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

The Trinity Aquifer stretches across the Texas Hill Country including Northern Bexar County. It has historically been one of the main sources of water for customers in far 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, Timberwood Park, and Oliver Ranch.

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 acre-feet per year. In 2021, SAWS delivered about 7,700 acre-feet of water meeting the needs of approximately 31,000 households.

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 water to enter the SAWS distribution system in early 2002. In 2021, SAWS produced approximately 2,000 acre-feet from Oliver Ranch supplying roughly 8,000 households.

Timberwood Project

The Timberwood Project is the smallest producing project delivering up to 2,000 acre-feet of Trinity Aquifer water from four wells in Northern Bexar County. However, in 2021 only 67 acre-feet of water was delivered to customers. Production from this project has decreased since Vista Ridge came online in 2020.

Combined, SAWS received approximately 9,700 acre-feet from these three Trinity Aquifer projects. This accounted for approximately 3.4 percent of SAWS’ total distribution in 2021.

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

1 acre-foot per year = 325,851 gallons