SAN JOAQUIN COUNTY — The San Joaquin County Board of Supervisors voted Tuesday to declare a state of emergency over the threat posed by invasive golden mussels in the Sacramento-San Joaquin Delta. The declaration cited the imminent threat the species poses to water delivery systems, agriculture and the broader environment.

In a resolution accompanying the declaration, local leaders urged Governor Gavin Newsom to expand the emergency declaration statewide and called on federal agencies to step in. The resolution stated: "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."

Golden mussels, known scientifically as Limnoperna fortunei, attach to hard surfaces such as pipes, pumps and other infrastructure. The mussels were first discovered in October 2024 at the Port of Stockton and have spread through the Sacramento-San Joaquin Delta since that initial discovery. By December 2024, the California Fish and Game Commission designated golden mussels as restricted, making it illegal to import, transport or possess them in the state.

Assemblymember Rhodesia Ransom expressed support for the emergency action. "My community in San Joaquin County is ground zero for this infestation, and we are already seeing the damage firsthand," she said. "If we don't act now, this will only get more expensive and harder to control," Ransom added.

A golden mussel was found on a boat at Folsom Lake in 2024. Authorities fined a boater $5,000 at Lake Tahoe for tampering with an inspection seal aimed at stopping the spread of the species.