Surface Water Projects

SAWS currently has three surface water projects in and around Bexar County that help meet SAWS’ yearly demand. In 2019, SAWS produced about 4 percent of its total demand from these surface water supplies.

Medina Lake

The Medina Project was established as San Antonio’s first surface water project in 2000. With access to almost 20,000 acre-feet per year, water stored in Medina Lake can be delivered to SAWS’ ultra-filtration membrane plant located on the Medina River in southwest Bexar County.

While the plant currently has a treatment capacity of up to 13,000 acre-feet per year, this supply has not been utilized since 2015.

During times of drought, Medina Lake is considered to have a zero firm yield. This classification is due to its small contributing watershed and location over the Edwards Aquifer Recharge Zone.

Western Canyon Lake

San Antonio’s second surface water project was established in April of 2006, delivering treated water from Canyon Lake to customers in Northwest and North Central San Antonio.

The Western Canyon project is a successful alliance between the GBRA (Guadalupe-Blanco River Authority) and water purveyors in Comal, Kendall and Bexar counties. SAWS has an agreement to receive a minimum of 4,000 acre-feet per year. In 2019, SAWS received about 8,000 acre-feet, which supplied approximately 32,000 households.

Lake Dunlap

Water from Lake Dunlap continues to serve northeast San Antonio. It is located on the Guadalupe River east of the city of New Braunfels and is made possible through an agreement with Canyon Regional Water Authority (CRWA).

SAWS has an agreement to receive up to 4,000 acre-feet per year of treated surface water from Lake Dunlap through the end of 2023, at which time the water volume is returned in basin and CRWA replaces this volume to SAWS with groundwater supplies. In 2019, CRWA delivered SAWS approximately 1,675 acre-feet of water, enough to supply 6,700 households.

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 constraints.

surface water map

1 acre-foot = 325,851 gallons