Invasive Mussel News

California Department of Fish and Wildlife (CDFW), Department of Water Resources, and California State Parks issued a joint press release on April 16, 2025 titled "California Takes Action to Halt Golden Mussel Invasions” announcing the development of a comprehensive Golden Mussel Response Framework developed by the Golden Mussel Task Force.

In addition, the California Department of Fish and Wildlife (CDFW) is offering $1 million in grant funding to boating facility operators to enhance efforts against invasive mussels, particularly the threat of golden mussels. This funding supports projects that help prevent the introduction and spread of invasive mussels in lakes, reservoirs and waterways, ensuring the long-term health of state waters. The grant solicitation and application link can be found on CDFW’s website.

California Department of Fish and Wildlife is relaying the following information received from the California Department of Food and Agriculture (CDFA). CDFW anticipates the following changes to CDFA's Border Protection Stations program operations will impact the interdiction and inspection of overland conveyances that may carry invasive mussels. Questions can be directed to CDFW via Invasives@wildlife.ca.gov or (866) 440-9530 and will be shared with CDFA.

The following information is being forwarded on behalf of the CDFA:

The State of California is currently facing a significant and ongoing budget deficit, and programs across CDFA are being required to implement budget reductions. In accordance with the budget reductions, the Border Protection Stations (BPS) Program will be reducing scheduled staffing levels to the minimum necessary to maintain safe operations for all working shifts, and will be reducing the hours of operation at multiple stations.

The following schedules of operation will be implemented effective April 1, 2025:

• Alturas: Open daylight hours
• Benton: Open daylight hours
• Blythe: Open 24/7
• Dorris: Open 24/7
• Hornbrook: Open 24/7
• Long Valley: Open 24/7
• Meyers: Open 8 hours per day
• Mt. Pass: Open 24/7
• Needles: Open 24/7
• Redwood Highway: Open daylight hours
• Smith River: Open daylight hours
• Topaz: Open 8 hours per day
• Truckee: Open 24/7
• Tulelake: Open daylight hours
• Vidal: Open 24/7
• Winterhaven: Open 24/7

For the stations open during daylight hours, they will be open for two shifts, which may vary seasonally from 14-16 hours.

Additionally, all stations are being instructed to focus on commercial traffic, with a primary focus on the compliance of high-risk agricultural commodities and the Program’s responsibilities for its cooperative agency agreements. Private vehicle inspections will be impacted by the reduced staffing levels, and should continue to be conducted as traffic and/or staffing allows.

And while all stations will continue to be scheduled for operation seven days per week, with the reduced available staffing there may be days where Station Managers will need to close operations for a day to ensure the safety of both program staff and the traveling public.

Golden mussel (Limnoperna fortunei), an invasive, non-native freshwater bivalve, was recently discovered in the Port of Stockton by California Department of Water Resources staff while conducting routine operations. Suspected golden mussels have also been identified at O’Neill Forebay in Merced County and are currently undergoing genetic testing for confirmation.

This discovery is the first known occurrence of golden mussels in North America. The species poses a significant immediate threat to the ecological health of the Delta and all waters of the state, water conveyance systems, infrastructure and water quality.

In waterways where this species is present, heavy encrustations of golden mussels have blocked municipal and industrial water intakes, necessitated ongoing biofouling removal, harmed native species in the ecosystem, increased water clarity due to intense filter feeding, and diminished water quality.

The California Department of Fish and Wildlife (CDFW), California State Parks, California Department of Water Resources (DWR), U.S. Fish and Wildlife Service, Bureau of Reclamation, and other state, federal, and local agencies regularly coordinate through the Aquatic Invasive Species program. This partnership aims to limit the spread of invasive species in California’s waterways, which cause damage to native species and the ecosystems they need to survive.

Golden mussels were likely introduced to California by a ship traveling from an international port. They are likely to spread throughout the Delta and through the water conveyance systems associated with it. Without containment, golden mussels are likely to spread to other freshwater bodies in California, and to other ports and inland waters of North America, and abroad.

Following the initial discovery of golden mussels in the Port of Stockton, observations of additional mussels have been made on monitoring equipment downstream. Species confirmation is pending for these organisms. Golden mussels are similar in appearance, biology, and impacts to quagga and zebra mussels and are a continued priority for prevention and containment in inland waters of Southern California and across the state.

Golden mussels are native to rivers and creeks of China and Southeast Asia. They are known to be established outside of their native range in Hong Kong, Japan, Taiwan, Brazil, Uruguay, Paraguay and Argentina. The initial introductions to these countries were also likely the result of ships from biofouling on the hulls and/or ballast water release. In most cases, the invaded range has expanded upstream from the point of introduction and inland from ports through local, human-mediated pathways. Within the invaded range significant impacts are widely documented resulting from the dense colonization of golden mussels on hard surfaces. The California Natural Resources Agency and its partners call upon everyone working and recreating in waters of the state to clean, drain and dry watercraft and equipment every time it is removed from a waterbody. This simple measure has served to prevent spreading quagga and zebra mussels and is equally effective in stopping the overland spread of golden mussels. DWR is now conducting boat inspections at O’Neill Forebay in an effort to reduce the spread of aquatic invasive species.

CDFW is continuing to work with state, local, and federal agencies to enhance monitoring efforts, communicate additional detection and response information, and coordinate on potential next steps. Please report organisms observed in California suspected to be golden mussels to CDFW’s Invasive Species Program. Include the specific location of the observation, and at least one clear close-up photograph of the organism, and your contact information. Submit reports via one of the following options:

Online at wildlife.ca.gov/Conservation/Invasives/Report
Via email to invasives@wildlife.ca.gov
Via telephone to (866) 440-9530

To prevent the spread of invasive mussels, be sure to clean, drain and dry your boats. For more information on golden mussels refer to CDFW's webpage: California’s Invaders: Golden Mussel. Learn more at California State Parks’ Division of Boating and Waterways webpage: dbw.parks.ca.gov/StopQZ.