Board of Supervisors
San Joaquin County Board of Supervisors Proclaims Local Emergency Over Invasive Golden Mussel Threat
April 28, 2026

Stockton, CA, – The San Joaquin County Board of Supervisors today proclaimed a local emergency in response to the growing threat posed by the invasive golden mussel in the San Joaquin Delta, urgently calling for strengthened State partnership, additional resources, and coordinated action to protect one of California’s most vital waterways.

The golden mussel poses serious risks to water conveyance systems, flood control infrastructure, agriculture, recreation, and the Delta ecosystem. Officials warn the species can rapidly colonize surfaces, clog pipelines, restrict water flows, and disrupt natural habitats.

The Delta remains a critical source of drinking water, agricultural production, economic activity, and recreation for San Joaquin County and communities throughout California. County leaders emphasized that while the State’s “Clean, Drain, Dry” campaign remains an important prevention tool, areas where the mussel has already taken hold require additional action.

“The Delta is central to San Joaquin County’s identity, and with more than two thirds of the Delta within our county, protecting it must remain a top priority,” said Supervisor Paul Canepa. “We appreciate the State’s partnership, but prevention alone is not enough where this species is already established. This declaration should serve as a warning across California that we need targeted solutions for the Delta and a serious conversation about mitigation.”

The Board agreed that a coordinated response is needed to protect boating access, fishing, public infrastructure, farms, and freshwater systems throughout the region.

District One Supervisor Mario Gardea said the threat extends far beyond recreation and requires immediate attention from every level of government. “Golden mussels affect far more than recreational boating. They threaten agriculture and critical local infrastructure, increase flood risks, and could bring major mitigation costs that taxpayers may ultimately bear. Stockton is ground zero for this issue, and we must ask, what invasive species comes next? That is why we need urgent action and strong regional coordination now.”

As part of the proclamation, the Board directed County staff through the Office of Emergency Services to continue coordinating with local, regional, State, and federal partners to pursue funding, technical assistance, mitigation strategies, and infrastructure protection resources. The Board will review the status of the emergency at least every 60 days, as required by law.

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Katie Piper,
Public Information Officer
Phone: 209-696-1853