In a startling development for California’s water system, state officials have confirmed the infestation of invasive golden mussels (Limnoperna fortunei) at two major Southern California lakes: Silverwood Lake in San Bernardino County and Pyramid Lake in Los Angeles County. The rapid spread of this highly destructive species from the Sacramento-San Joaquin Delta to the southern reaches of the State Water Project marks a new chapter in the state’s ongoing struggle to safeguard both water infrastructure and delicate aquatic ecosystems. The golden mussel is notorious worldwide for its ability to multiply quickly, clog pipes and screens, destabilize local ecology, and create costly headaches for urban, agricultural, and recreational water systems.