West Basin backs legislative package to combat golden mussel threat to California water infrastructure

West Basin backs legislative package to combat golden mussel threat to California water infrastructureFollowing the October 2024 detection of golden mussels in the California Delta, the West Basin Municipal Water District has formally supported state legislation designed to fund containment efforts and protect imported water deliveries for groundwater recharge.

Golden mussels attach to infrastructure in dense clusters, clogging pipes and pumps, with eradication currently deemed unfeasible.

The district committee backed AB 1894, which prevents agencies from prohibiting imported water deliveries for groundwater replenishment without proven health and safety risks.

West Basin also supported AB 1772 and AB 2032 with amendments, seeking to streamline control measures and establish flexible decontamination standards at reservoirs.

In a separate infrastructure update, staff reported that the Metropolitan Water District's pipeline rehabilitation program costs have increased to $3.5 billion, with completion pushed to 2050.

The Water Policy and Legislation Committee of the West Basin Municipal Water District voted on July 15, 2026, to advance support for three California state assembly bills aimed at mitigating the operational and financial impacts of invasive golden mussels. First detected in the California Delta in October 2024, golden mussels pose a severe threat to water infrastructure. Water Policy and Resource Development Analyst Augustine Hong told the committee that the species attaches to infrastructure in dense clusters, clogging conveyances, pipes, and pumps. With eradication currently deemed unfeasible, the state's focus has shifted entirely to containment. Imported water from the State Water Project remains a critical component of West Basin's supply portfolio. District staff emphasized that water agencies and ratepayers should not bear the sole financial burden of controlling the invasive species. Hong noted that Governor Gavin Newsom's January budget proposed utilizing $20 million from Proposition 4 climate bond funds to create eight new positions dedicated to implementing state-approved mussel control plans. The committee recommended full support for Assembly Bill 1894. Hong noted the legislation addresses a specific local hurdle in Los Angeles County, where imported water deliveries for groundwater recharge in spreading basins have been restricted due to mussel concerns. AB 1894 would prohibit public agencies from blocking imported water deliveries unless there is a documented health and safety risk. The committee also adopted "Support if Amended" positions for two other bills. For AB 1772, which establishes statewide monitoring and decontamination standards at recreational reservoirs, West Basin aligns with the Metropolitan Water District (MWD) in seeking amendments that allow reservoir managers flexibility to tailor decontamination frameworks to specific water bodies. For AB 2032, which streamlines control measures and research, the district supports broadening the language to include all invasive species, including quagga and zebra mussels. In separate infrastructure updates, Manager of Water Policy and Resources Matt May briefed the committee on MWD's Prestressed Concrete Cylinder Pipe (PCCP) Rehabilitation Program. To moderate the impact on its capital improvement budget, MWD is scaling the program to one major relining project per year. This revised approach pushes the overall completion date of the 29-mile pipeline rehabilitation to 2050, with program costs now projected at approximately $3.5 billion.