City officials in Austin have begun construction on a $1.5 billion expansion of the Walnut Creek Wastewater Treatment Plant, a project aimed at increasing capacity and upgrading aging infrastructure while maintaining full operations during construction.
The Walnut Creek facility, originally built in 1977 when Austin’s population was just over 320,000, now serves more than half of the city’s residents. With Austin’s population exceeding one million, the plant currently treats up to 75 million gallons of wastewater per day. The expansion will increase capacity to 100 million gallons per day, aligning with projections that the city’s population could reach 1.5 million by 2040 and meeting regulatory requirements set by the Texas Commission on Environmental Quality.
City leaders said the project is intended to support long-term service reliability and environmental protection, particularly for the Colorado River downstream of Austin. The plant has received national recognition, including the National Association of Clean Water Agencies’ Platinum Peak Performance Award.
In addition to increasing capacity, the project includes several upgrades to treatment processes and infrastructure. Planned improvements include advanced technology to reduce nutrients linked to algae growth, a shift from chlorine gas to ultraviolet disinfection, and the installation of odour control systems such as biofilters and activated carbon filters. The project also includes the construction of a flood wall to protect the facility during extreme weather and modernization of ageing components.
Officials said the expansion is also expected to support local employment, with workforce development tied to initiatives such as the Austin Infrastructure Academy, a collaboration among government, education, and business partners.
The Walnut Creek plant is one of two regional wastewater treatment facilities in Austin. Treated water is partially reused for irrigation and other non-drinking purposes through the city’s reclaimed water system, with the remainder returned to the Colorado River.
Funding for the project will come from a mix of local, state, and federal sources. This includes up to $1 billion in low-interest financing from the U.S. Environmental Protection Agency’s Water Infrastructure Finance and Innovation Act program and $59 million from the Texas Water Development Board’s Clean Water State Revolving Fund, along with additional funding from Austin Water.
MWH Constructors will serve as the construction manager at risk, and AECOM is responsible for design engineering.
