San Marcos Water Treatment Plant Division

This division operates and manages the City of San Marcos' water treatment plant, recently upgraded to 21 mgd. Raw water from Canyon Reservoir is pumped from Lake Dunlap through a 24-mile pipeline, treated to meet state and federal drinking standards, and delivered to the cities of San Marcos and customers of the GBRA IH35 Treated Water Transmission System for distribution.

The plant is owned by the City of San Marcos, which selected GBRA to be the contract operator of this $15.5 million facility. Operations began in January 2000 with an initial treatment capacity of 6 mgd, and was expanded to 21 mgd in 2009 to meet future regional growth requirements.

The plant's water source is stored water from Canyon Reservoir, contracted by the City of San Marcos and customers of the GBRA IH35 Treated Water Transmission System. GBRA built and owns the pump station at Lake Dunlap that diverts the stored water, and the 24 miles of pipeline that deliver the water to the plant for treatment.

The conversion to surface water has reduced the City of San Marcos' daily pumping from the Edwards Aquifer by an average of 75%. Reduced pumping protects the springflow contributions to the Guadalupe River from the Comal Springs and the San Marcos Springs. Existing city wells can be reserved for use as supplemental resources during peak usage periods.

The San Marcos Water Treatment plant consistently meets the requirments of the Texas Commission on Environmental Quality Texas Optimization Program (TOP), a voluntary, non-regulatory program designed to dramatically improve the performance of existing surface water treatment plants without major capital improvements.

  • Location: San Marcos, Texas
  • Startup Date: January 2000
  • Capacity: 21 mgd
  • Service Area: Cities of San Marcos, Kyle and Buda, and unincorporated areas along IH-35 in northern Hays County.
  • Service Population: 70,000


Kasey Belote, Plant Manager
Phone: 512-353-3888

© 1998 Guadalupe-Blanco River Authority