City of San Marcos Surface Water Treatment Plant

The Surface Water Treatment Plant (SWTP) is responsible for ensuring all water production facilities and water storage tanks are operational and in compliance with regulatory requirements to provide safe drinking water to the community. This includes coordinating all ground water (water drawn from wells) production with the Surface Water Treatment Plant, ensuring adequate water supply is available to all residents.

In 2019, the City produced approximately 8,971 acre feet, or 2.92 billion gallons of water. 20% percent of this water came from the Edwards Aquifer and the remaining 80% of the water produced was surface water coming from Canyon Lake. As part of routine operations, each of the 9 water production/storage locations are monitored continually by computer control systems and inspected on a daily basis. Production of water is regulated by TCEQ and the Edwards Aquifer Authority, and all personnel who perform duties in this area are certified water system operators.

Owned by the City of San Marcos, the SWTP is operated under contract to the City by the Guadalupe Blanco River Authority (GBRA). Raw water is delivered to the SWTP via water lines from Lake Dunlap which is located northeast of New Braunfels. The Cities of Kyle and Buda, as well as other water supply corporations, also receive treated water from this facility. GBRA, under terms of the regional agreement, funded expansion of the SWTP from 9 MGD to 21 million gallons per day (MGD) to serve future demands of their contract wholesale customers.