An 'out of control' species of mussel is threatening California's water infrastructure
Officials in San Joaquin County declared an emergency due to the infestation.
An invasive species of mussel is becoming more of a concern in California as it overtakes ecosystems and impacts infrastructure, according to officials.
Golden mussels, native to China and Southeastern Asia, were first detected in October 2024 by California Department of Water Resources staff who were conducting routine operations in the Port of Stockton, a CDWR spokesperson told ABC News. The discovery was the first known occurrence of golden mussels in North America.
Since then, the mussels have spread quickly up and down the West Coast -- to the north, in the Bay Area, and to the south down to Los Angeles and San Diego, according to a map from the California Department of Fish and Wildlife. The species are highly efficient filter feeders and form dense colonies, according to the CDWF.
On Tuesday, San Joaquin County officials declared an emergency over the threat posed by the golden mussel.
All five county supervisors voted in favor of the declaration during Tuesday's board meeting, including Supervisor Paul Canepa who described the situation as "out of control."
The species is posing a significant immediate threat to the ecological health of the Sacramento-San Joaquin Delta, the CDWR spokesperson said. Heavy encrustations of golden mussels have blocked pipes in municipal and industrial water intakes, which has necessitated costly biofouling removal.
Water conveyance systems, infrastructure and water quality all over the state have been impacted by the presence of golden mussels, according to the DWR.
Golden mussels can reproduce quickly -- aided by the fact that they have no natural predators and are less sensitive to variability in water chemistry and temperatures, said Pam Marrone, executive chair and co-founder of the Invasive Species Corporation, a company that seeks environmentally responsible solutions to ecological threats.
A single female golden mussel can produce up to 1 million offspring per year, Hilary Crowley, a legislative officer for San Joaquin County, told the board on Wednesday.
A floodgate just completed in 2024 that cost $100 million is among the infrastructure clogged with the invasive species, Crowley said. The floodgate will require an expensive removal of the mussels.
The species was likely introduced to California by a ship traveling from an international port, the CDWR spokesperson said. It has also spread to South America, including Argentina, Brazil, Bolivia, Paraguay and Uruguay, according to the CDWF.
Other environmental impacts include loss of native and game fish, according to the CDWR.
The filter feeders eat everything that enters the water, causing huge algae blooms to grow around them, Marrone told ABC News. Oxygen is then depleted, and fish are unable to survive.
Mussels can be treated using chlorine, copper and Zequanox, made from a naturally occurring bacterium that causes the mussels to stop feeding and die, Marrone said. Hot water can also be used, the CDWR spokesperson said.
Researchers are currently conducting laboratory testing of potassium chloride on golden mussel mortality and completing a design for ultraviolet disinfection systems, according to the CDWR.
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