Growing threat from invasive mussels

California’s water infrastructure is facing a rapidly growing threat from invasive mussels, including quagga, zebra, and the recently introduced golden mussel. First detected in North America in the Sacramento-San Joaquin Delta in October 2024, the golden mussel can tolerate a wider range of temperatures, salinities, and water conditions than quagga and zebra mussels, increasing the number of water bodies vulnerable to infestation. State officials have warned that these invasive species can clog pipelines, screens, pumps, canals, and treatment facilities, disrupt water delivery, agriculture, hydropower production, and flood control systems.

As the California Department of Water Resources noted, “the golden mussel poses a serious threat to California’s water delivery systems, the environment, and recreational opportunities.”

Copper-based treatment programs offer a valuable tool in an integrated mussel management strategy. By targeting mussel larvae and helping prevent population establishment, copper treatments can reduce biofouling, protect critical infrastructure, and lower long-term maintenance costs. While no single solution will eliminate the threat, proactive monitoring, early intervention, and targeted copper treatment programs can help water agencies, irrigation districts, and facility operators minimize impacts and maintain reliable water delivery. As invasive mussels continue to spread across California, prevention and control efforts are becoming more important than ever.