Project Background

Major Rehabilitation of First Aqueduct Complete

In January 2021, the Water Authority completed major construction rehabilitation activities on the historic First Aqueduct in North San Diego County. The project renovated and replaced dozens of structures on two large-diameter pipelines, including Pipeline 1, which delivered the first imported water to the San Diego region in 1947 and remains a vital part of the regional water delivery system.

The timely rehabilitation of the First Aqueduct is part of the Water Authority’s proactive asset management program. A key element of providing safe and reliable water supplies is continually assessing the agency’s 310 miles of large-diameter pipeline and making the upgrades necessary to continue serving the region. That work is funded through water bills paid by residents and businesses across the county to sustain the region’s $245 billion economy and quality of life.

The Northern First Aqueduct project began in early 2019 and was one of the most complicated pipeline retrofits in the Water Authority’s history. The upgrades included replacing 14,500 linear feet of interior lining on the steel pipe sections of Pipeline 1, removing 16 associated structures and retrofitting 46 structures, all while ensuring regional water service remained safe and reliable. In addition, redundant connections to six flow control facilities were added between the two pipelines to improve the aqueduct’s operational flexibility.

The next scheduled work on the First Aqueduct – the Southern First Aqueduct Structures Rehabilitation project – from Escondido to its terminus at the San Vicente Reservoir is scheduled to begin in Spring 2024.

Rehabilitating large-diameter pipelines to maintain critical infrastructure

Within this section of the Water Authority’s system, Pipelines 1 and 2 are between 48-inches and 54-inches in diameter. Pipeline 1 was constructed in 1947 and Pipeline 2 in 1954 to transport the first imported water into the San Diego region. A condition assessment completed in 2014 determined it was time to replace interior lining of the pipeline to ensure future water reliability.