Council members approved a $1.5 billion expansion contract for the facility, which treats roughly half of Austin’s wastewater.

AUSTIN, Texas — Austin leaders on Thursday approved a funding increase for one of the city’s two major wastewater treatment sites. 

Council members approved a contract for a $1.5 billion expansion at the Walnut Creek Wastewater Treatment Facility, located on FM 696.

The initial plan was to spend $900 million on the project’s construction, but Austin Mayor Kirk Watson said estimates have increased and inflation has prompted higher costs.

The facility’s last expansion was more than 20 years ago, back in 2005. 

The plant originally opened in 1977, where it was able to treat roughly 40 million gallons of water daily. The plant has since exceeded 90% capacity on multiple occasions, according to KVUE’s reporting from March 2025. 

“It is definitely a generational project for the future of Austin,” assistant director of engineering and technical services for Austin Water Charles Celauro told KVUE at the time. 

The new expansion will allow for 25 million additional gallons to be treated daily, raising the capacity to roughly 100 million each day. Additional improvements would include the addition of 12-foot floodwalls and upgraded basins. 

According to the City of Austin’s website, the plant treat’s roughly half of the city’s wastewater, returning water to the Colorado River. 

Austin Water expects the expansion to be complete by 2031.Â