COWI to Manage Construction of Syphon Reservoir Expansion in California

COWI has been appointed by the Irvine Ranch Water District (IRWD) as construction manager for the Syphon Reservoir Improvement Project, the largest project in IRWD’s history and one of Southern California’s most significant water infrastructure upgrades.Working in joint venture with GFT (formerly Gannett Fleming), COWI will provide full construction management services. This includes pre-construction constructability reviews, support for contractor bidding, budget and schedule control, resident engineering, quality assurance, and formal risk management. The joint venture will also collaborate with IRWD’s environmental monitoring and public outreach teams to protect the local environment and community during the works.The project will expand Syphon Reservoir’s storage capacity ten-fold, enabling the storage of up to 5,000 acre-feet of recycled water. By increasing storage for non-potable supplies, the scheme will enhance regional water supply reliability, support climate resilience, and reduce the costs of imported water.

California faces growing pressure on its water resources due to climate change and population growth. The Syphon Reservoir expansion is a step towards safeguarding sustainable supplies and offers a model for other public agencies facing similar challenges.

IRWD pioneered recycled water infrastructure with the introduction of the globally recognised “purple pipe” system. The expansion of Syphon Reservoir builds on this legacy, enabling more recycled water to be stored and reused for irrigation and other non-drinking purposes, thereby reducing demand on potable supplies.

COWI’s involvement underlines its growing role in shaping Southern California’s water infrastructure. Previous projects include Anderson Dam Phase 1, Lafayette and Briones Reservoirs, Chabot Dam, Folsom Dam, San Vicente Dam, Lake Mathews, Nacimiento Lake, Lake Calavera, and Gene Wash and Copper Basin dams.