Karmactive Staff
The golden mussel has arrived in California, and water managers are racing to stop its spread before this thumbnail-sized invader wreaks havoc on our pipes, pumps, and wildlife.
First detected in October 2024 at the Port of Stockton, these mussels from Asia have now been found in O’Neill Forebay, San Luis Reservoir, and most recently at Folsom Lake. This marks the first time these invasive mollusks have appeared in North America, triggering a statewide emergency response.
“This is a serious challenge requiring long-term commitment,” said CDFW Director Charlton Bonham in a recent statement. “We’re mobilizing every resource available to contain this threat.”
Unlike the zebra and quagga mussels that have plagued the Great Lakes region, golden mussels thrive in warmer waters and multiply even faster – a female can produce up to one million eggs annually. They form dense colonies that clog water pipes, damage infrastructure, and disrupt native ecosystems.
Why These Mussels Matter to Everyone
For regular Californians, the golden mussel invasion threatens our water in ways both big and small. These tiny invaders can:
- Clog drinking water intake pipes that serve two-thirds of California residents
- Damage to irrigation systems is critical to the state’s agriculture
- Foul boat motors and hulls create headaches for recreational users
- Alter freshwater ecosystems by filtering out plankton needed by native species
“We’re working to safeguard water infrastructure through coordinated action,” explained John Yarbrough, Deputy Director of the State Water Project. “The economic costs of inaction are simply too high.”
South America has battled golden mussels since 1991, with costs reaching $30-50 million yearly from clogged hydroelectric plants and water systems. Some facilities there spend up to $100,000 per mile of pipe for de-fouling operations.
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What California Is Doing About It
In April 2025, state officials unveiled the “Golden Mussel Response Framework,” backed by a $1 million grant program to help marinas install decontamination stations and boost inspections.
All trailered boats entering high-risk waterways now face mandatory inspections and a 30-day quarantine period. Boaters must follow the “Clean, Drain, Dry” protocol:
“Remove all visible plant material and mud, drain every drop of water, including livewells and bilges, then thoroughly dry your equipment for at least 30 days,” advises CDFW’s newest guidance. “Even a tiny mussel or microscopic larva can start a new colony.”
Special K-9 detection teams now patrol boat ramps, while biologists use cutting-edge DNA sampling to detect mussels before they become visible. These “eDNA” techniques can identify genetic traces of mussels in water samples, allowing early intervention.
Tracking the Source and Stemming the Spread
Scientists believe the mussels likely arrived via ballast water from international shipping, exposing a regulatory gap in California’s 2019 ballast water discharge rules. Current regulations require initial testing but lack mandatory follow-up after mid-ocean voyages.
The public plays a crucial role in fighting this invasion. Residents can report sightings through CDFW’s invasive species hotline (866-440-9530) or email [email protected]. These tips have already identified three new locations where the mussels are spreading.
Volunteer watershed monitoring groups are being trained to assist with early detection, giving community members a hands-on role in protecting local waterways.
“This isn’t just about infrastructure and economics,” one biologist noted during a recent training session. “It’s about preserving California’s aquatic ecosystems for future generations.”
What Happens Next
Control efforts in Brazil have shown that chlorine treatments, copper-based coatings, and mechanical removal can reduce mussel populations by 60-90 percent, offering hope that California can manage the invasion with sustained effort.
Researchers at CDFW and USGS are sequencing the complete mitochondrial genome of these mussels to confirm their identity and trace their introduction pathway, which may help prevent future invasions.
The recent Folsom Lake quarantine was lifted on May 12, 2025, after follow-up testing showed no additional mussel detections, demonstrating that rapid response can be effective when the public cooperates with prevention measures.
Water managers are now integrating mussel management into broader water resilience planning, recognizing that protecting infrastructure from invasive species must become a permanent part of California’s water security strategy.
For now, the state’s message to boaters and water users remains simple: stay vigilant, follow inspection requirements, and help keep these golden invaders from gaining a permanent foothold in California’s waters.
