Major Milestone Reached on San Diego’s Historic First Aqueduct

The San Diego County Water Authority is at the halfway point on a critical construction project to extend the life of the historic First Aqueduct and ensure continued delivery of safe and reliable water supplies for the region.  

Work on the project, known as the Southern First Aqueduct Facilities Improvement Project, is expected to run through summer 2026 with renovations to 99 structures along two large diameter pipelines that run from north to south county. 

 “The First Aqueduct has served our region for over 70 years, and this investment is about making sure it continues to do so reliably,” said Nick Serrano, chair of the Water Authority Board of Directors. “This project is a great example of our water bills at work – ensuring that the infrastructure delivering safe and clean water to our homes and businesses remains strong for generations to come.”  

The project represents one of the most extensive maintenance efforts in the agency’s history. The First Aqueduct serves 11 water agencies countywide. Improvements are focused on two parallel pipelines that were construction in the late 1940s and 50s.  

The three-and-a-half-year project stretches 21-miles starting north of Escondido and east of Interstate 15, continuing south to Slaughterhouse Canyon in unincorporated San Diego County and ending at the San Vicente Reservoir in Lakeside. Along the way the work crosses Escondido, Poway, Rancho Bernardo and parts of unincorporated San Diego County.  

Funding for the $66 million effort comes from water bills across the region as part of the Water Authority’s Capital Improvement Program.  

Phase One of the work began in spring 2024 on Pipeline 2 structures. That work is scheduled to conclude at the end of February with Pipeline 2 being put back in service. The second phase will take Pipeline 1 out of service so that

work on its structures can begin. By working on the parallel pipelines separately, the Water Authority keeps one pipeline in service and minimizes potential for interruptions to water delivery during construction. 

 “As Phase One of the project moves toward completion, the Water Authority is grateful to the many neighbors and property owners impacted by the construction for their patience and support as this vital work continues,” Serrano said. “By making these improvements before they become urgent, we avoid more costly repairs and reduce the overall cost of system maintenance, while keeping our water supply safe and the taps flowing.” 

To expedite the transition to Phase Two of the project, construction will take place around the clock for 10 days from Feb. 23 to March 4. Night work is planned for seven locations. Most of the 24-hour worksites are on undeveloped land with negligible impacts on residents or businesses.  

The Water Authority is coordinating with local water agencies to minimize the potential for interruptions to water service during construction. Residents with questions or concerns about water service should contact their local water supplier, while questions about the project should be directed to the Water Authority at .  

For more information about the Southern First Aqueduct Facilities Improvement Project, including an interactive map where viewers can find work sites near their own addresses, visit www.sdcwa.org/first-aqueduct.