The completion of the Horsethief Canyon Water Reclamation Facility expansion marks a major infrastructure milestone for Southern California’s growing Temescal Valley community. The $33 million project, led by Elsinore Valley Municipal Water District (EVMWD), increases wastewater treatment capacity while supporting long-term water management and regional development.
The district recently celebrated the completion of the project with a ribbon-cutting and valve-turning ceremony attended by more than 60 community members, regional partners, and developers.
The upgraded facility expands treatment capacity from 0.5 to 0.8 million gallons per day (MGD), providing wastewater services for approximately 1,200 homes. As residential and commercial development continues across Temescal Valley, the expansion helps ensure reliable and efficient wastewater infrastructure to support future growth.
According to EVMWD, the project represents a significant investment in the region’s long-term water infrastructure planning.
Public-private partnership supports Horsethief Canyon Water Reclamation Facility expansion
The Horsethief Canyon Water Reclamation Facility expansion also marks the district’s first project delivered using a design-build model. Despite supply chain disruptions during the COVID-19 period, the project was successfully completed through close coordination between public and private stakeholders.
Through collaboration with four regional developers, approximately 65% of the project cost was privately funded. This approach helped reduce financial pressure on existing customers while enabling critical infrastructure improvements to move forward.
“Projects like Horsethief Canyon demonstrate what is possible when innovation, stewardship, and collaboration come together,” said EVMWD General Manager Greg Thomas.
“This facility reflects our commitment to responsible infrastructure planning — delivering lasting value for our customers and our community.”
Aerial view of the expanded Horsethief Canyon Water Reclamation Facility in Temescal Valley, California.
Membrane bioreactor technology improves wastewater treatment
The upgraded facility incorporates advanced membrane bioreactor (MBR) technology, which combines biological treatment with membrane filtration to remove nutrients and produce high-quality effluent.
MBR systems enable wastewater treatment plants to operate within a compact footprint while producing cleaner effluent suitable for reuse applications. The Horsethief Canyon facility’s treated water can support non-potable uses such as landscape irrigation and potential groundwater recharge, both important capabilities in water-scarce Southern California.
The facility has also been designed with automation and remote monitoring capabilities, allowing operators to manage treatment processes more efficiently.
Program management and owner’s advisor services for the project were provided by Carollo Engineers, supporting EVMWD from the design phase through construction.
“What EVMWD accomplished here is remarkable — bringing together four private development partners, embracing a new project delivery model, and seeing it through despite significant supply chain challenges,” said Carollo Senior Project Manager and Vice President Jeff Weishaar.
“The Horsethief Canyon WRF expansion is a testament to what thoughtful program management and strong partnerships can achieve, delivering resilient, future-ready water systems for the Temescal Valley community.”
The ceremony also drew representatives from federal, state, and local offices, including representatives from the offices of Congressman Ken Calvert, Senator Kelly Seyarto, and Assemblywoman Sabrina Cervantes. Attendees were invited to tour the upgraded facility to see how the improvements will support long-term community water management.
