Southern First Aqueduct Facilities Improvement

Project Background


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The San Diego County Water Authority’s historic First Aqueduct delivers both treated and untreated water from just south of the Riverside County/San Diego County border to San Vicente Reservoir near Lakeside. The First Aqueduct comprises two critical pipelines which are between 48 and 54 inches in diameter. Both pipelines in the aqueduct were constructed by the federal government soon after World War II to transport imported water to the San Diego region.

The First Aqueduct continues to be a vital part of the regional water delivery system, providing water service to 11 of the Water Authority’s member agencies, and ensuring regional water service remains safe and reliable. While the system has been reliable for many decades, 99 above- and below-ground facilities connected to the First Aqueduct are due for a combination of improvements, rehabilitation, maintenance, mechanical replacement, and engineering upgrades.

The Southern First Aqueduct Facilities Improvement Project will improve 99 unique aqueduct support structures in streets, along access roads and within utility easements for Pipeline 1 and Pipeline 2 of the First Aqueduct — two critical, regional water pipelines are capable of transporting up to 120 million gallons of water per day to the San Diego region.

These structures contain blow-off valves for releasing water and draining the pipeline, pipeline access points, or air valves for releasing and letting air into the pipelines. Connections to existing flow-control facilities are also being expanded between the two water pipelines to improve operational flexibility and maintain delivery to member agencies during construction.

The project’s estimated cost is $66 million. The project is funded as part of the Capital Improvement Program (CIP), which is approved by the Water Authority’s Board of Directors. This investment is expected to extend the life of the pipelines and their supporting structures by more than 50 years.

Project Status: Current