Trinity Aquifer

Small Projects Offer Big Step in Water Resource Diversification

Introduced in 2002 as a new source for San Antonio’s water supply, the Trinity Aquifer was the first non-Edwards Aquifer drinking water through SAWS pipelines. It began with two small projects – Oliver Ranch and Bulverde Sneckner Ranch – but now a number of production facilities use the Trinity Aquifer as a water resource, serving ratepayers in the high-growth area of north central San Antonio. As part of the 2017 Water Management Plan, the Trinity Aquifer plays a major role in providing additional sources to enhance the region’s water supply.

Oliver Ranch Project

The Oliver Ranch project is located in north central Bexar County where it provides Trinity Aquifer water to SAWS service areas. Water from this project was the first non-Edwards water to enter the SAWS distribution system. Under an initial 10-year contract, delivery of water to the SAWS system began in February 2002. A new 15-year contract was signed, effective July 1, 2010, with the option to extend for an additional 10 years. Currently, water is produced and chlorinated on the Oliver Ranch site and pumped to the SAWS Indian Springs Storage tank.

Bulverde Sneckner Ranch Project

The Bulverde Sneckner Ranch (BSR) project, also in north Bexar County, is in close proximity to the Oliver Ranch project. A total of four wells were completed on the property by SAWS. Like the Oliver Ranch project, water is chlorinated at the Oliver Ranch facility site. Delivery of water to the SAWS system began in June 2003. The original contract had an initial term of five years with three 5-year renewal options. In January 2006, an amended and restated contract was signed for a 15-year, 1 1/2-month timeframe through Feb. 15, 2020 with a possible 6-year extension. Hydrologic modeling was conducted for this property in conjunction with the Oliver Ranch property.

This map shows the area that began receiving water from the Trinity Aquifer
in February 2002.
Click on map for larger image.

Water Exploration Company, Ltd.

When San Antonio Water System assumed ownership of the former Bexar Metropolitan Water District in 2012, the utility also took over an existing water supply agreement with Water Exploration Company, Ltd., (WECO) for the purchase of water from the Trinity Aquifer.

SAWS renegotiated the water supply contract for a term of 15 years, with two optional five-year extensions. Total cost of purchased water depends on the amount produced.

Terms of the water supply agreement include:

  • As of July 1, 2013, SAWS is obligated to purchase up to 17,000 acre-feet* per year in monthly increments not to exceed 1,417 acre-feet*, if water is available for production.
  • SAWS pays for delivered water, meeting all state and federal drinking water standards.
  • Pumping by WECO may not reduce the Trinity Aquifer below 600 feet mean sea level at test wells.

What are the Benefits to the Trinity Aquifer

These projects augment water supply to one of the city’s highest growth areas. By utilizing this water source, as opposed to pushing Edwards Aquifer quickly, SAWS customers save on operating and energy costs.

More Trinity Aquifer Project Facts

  • SAWS originally signed contracts in February 2000 with the Massah Development Corporation and the BSR Water Supply Company to purchase water from public supply wells completed in the Trinity Aquifer system.
  • SAWS and Massah Corporation signed a new contract in July 2010, under which SAWS will purchase water from public supply wells completed in the Trinity Aquifer system. This agreement will remain in force for 15 years with an option to extend another 10 years.
  • SAWS signed an amended and restated contract with BSR in January 2006 for 15 years and 1 1/2 months with a possible 6-year extension.
  • The source of the water comes from the Lower Glen Rose and Cow Creek aquifers within the middle of Trinity Aquifer.
  • Water is pumped directly to the 3 million-gallon Oliver Ranch Water Storage Tank, near Bulverde Road and U.S. 281 North, and is then transferred to the Indian Springs Water Storage Tank near Bulverde and Smithson Valley roads or the Winchester Water Storage Tank near U.S. 281 North and Marshall Road. Water is provided to the SAWS system from any of these locations.
  • The projects’ capital costs were about $12.8 million.