A state of emergency has been declared in San Joaquin County as officials warn a fast-spreading invasive species is threatening California’s critical water systems.

The county’s Board of Supervisor’s voted Tuesday to issue the emergency declaration, citing the “imminent threat” posed by golden mussels in the Sacramento-San Joaquin Delta, according to FOX40.

In a resolution, local leaders urged Gavin Newsom to expand the emergency statewide and called on federal agencies to step in.

Golden mussels — an invasive species known scientifically as Limnoperna fortunei — attach to hard surfaces like pipes, umps and other infrastructure, raising concerns about potential damage to water delivery systems, agriculture and the broader environment.

Officials said current state-level efforts “do not sufficiently address” the growing infestation, warning the scale of the threat exceeds what the county can handle.

“The scale, complexity and regional nature of this threat exceed the capacity of San Joaquin County to effectively respond without additional state and federal support,” the resolution stated.

The mussels were first discovered in October 2024 at the Port of Stockton and have since spread through the Delta.

By December, the California Fish and Game Commission designed the species as “restricted,” making it illegal to import, transport or possess in the state.

Earlier this month, Assemblymember Rhodesia Ransom warned the window contained the infestation is quickly closing.

“My community in San Joaquin County is ground zero for this infestation, and we are already seeing the damage firsthand,” she told FOX40. “If we don’t act now, this will only get more expensive and harder to control.”

There are already signs of the species spreading beyond its initial foothold.

A golden mussel was found on a boat in Folsom Lake last year, while authorities recently fined a boater $5,000 at Lake Tahoe for tampering with an inspection seal aimed at stopping the spread.

Officials warn the infestation could have sweeping consequences if left unchecked — particularly for California’s fragile water infrastructure and supply.

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