Invasive Mussel News

The California Department of Fish and Wildlife (CDFW)'s Invasive Mussel Control Plan Guidance document is intended to provide guidance on developing an invasive mussel control plan (Control Plan) to public and private agencies that operate a water supply system where invasive mussels have been detected. The Control Plan Template (Appendix A) is offered as a tool to assist water supply system agencies, and others, in developing a Control Plan that complies with the requirements under Fish and Game Code Section 2301 and California Code of Regulations, Title 14, Section 672 and 672.1. Use of the template, while recommended, is not required for compliance.

The guidance is available on CDFW's Quagga/Zebra Mussel webpage under the heading Invasive Mussel Control Plan Development and on the Golden Mussel webpage under the heading Additional Information, Waterbody Managers.

CDFW staff are available to assist throughout the development of a Control Plan. Please contact the CDFW Invasive Mussel Regional Scientist (PDF) based on the CDFW Region where the water supply system is located. If the water supply system spans multiple CDFW regions contact invasive@wildlife.ca.gov for assistance.

CDFW News | CDFW Confirms Northernmost Detection of Golden Mussel in Port of West Sacramento

The California Department of Fish and Wildlife (CDFW) is notifying the public and officials with the city of West Sacramento and Yolo and Sacramento counties that invasive golden mussels have been found in and around the Port of West Sacramento. 

This is the northernmost detection of golden mussel since the species was discovered in the Port of Stockton in the Sacramento-San Joaquin Delta in 2024. 

CDFW staff monitoring for golden mussel presence collected one mussel between the Jefferson Boulevard overpass and the west lock, and a second near the intersection of Boathouse Road and Stone Boulevard. The mussels were sent to CDFW’s genetics lab that confirmed on June 25 the specimens were golden mussel. Additional surveys around the docks in Washington Lake found additional mussels.  

It is believed the golden mussels found in the Port of West Sacramento are from a source population within the vicinity. Golden mussels are harmful to aquatic ecosystems, water conveyance systems and water infrastructure. 

Anyone boating or recreating on waterways around the Sacramento area, and throughout the Delta, should take precautions to stop the spread of golden mussel further upstream and overland on watercraft and equipment used in mussel-infested waters. Golden mussels attach to almost any underwater surface, including but not limited to boats, ropes, buoys and aquatic plants that entangle on anchors and trailers. 

Clean, Drain, Dry — inspect your watercraft, kayak, life vests, paddles and anything that touched the water every time it is removed from a water body. Remove all debris, animals, and plants, and dispose of them in the trash. Drain all water from ballasts, bilges and live wells. Lastly, allow everything to dry until moisture is no longer present. 

Through the continued efforts by boaters and others recreating on California’s waters, golden mussel can be prevented from spreading to waters not connected to the Delta. 

Help CDFW monitor the state’s waters for golden mussel by reporting organisms suspected to be golden mussel to CDFW’s Invasive Species Program. Include the specific location of the observation, at least one clear close-up photograph of the organism and your contact information. 

Submit reports via one of the following options: 

• Online at Report Golden Mussel
• Via email to invasives@wildlife.ca.gov
• Via telephone to (866) 440-9530

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Media Contact:  
Krysten Kellum, CDFW Communications, (916) 825-7120 

Golden Mussel Detections in California

Martinez Reservoir

September 8, 2025 – juvenile mussels were discovered on a settlement plate in Martinez Reservoir, Contra Costa County. The reservoir is the terminal reservoir of the Contra Costa Canal and receives water from the Delta. The mussels were genetically confirmed as golden mussel by polymerase chain reaction (PCR) analysis and DNA sequencing.

Santa Ana Valley Pipeline

September 29, 2025 – golden mussel veligers were detected by cross-polarized light microscopy (CPLM) in plankton samples collected at two routine sampling locations on the Santa Ana Valley Pipeline located downstream of Silverwood Lake and the Devil Canyon Powerplant, San Bernardino County. The samples were collected on September 23rd and 29th. The veligers were genetically confirmed by PCR analysis and DNA sequencing.

DWR, in coordination with partner agencies, has implemented regular inspections and maintenance at State Water Project facilities to minimize the effects of golden mussels. The discovery of golden mussels poses no imminent impacts to water quality or DWR’s ability to deliver water to 27 million Californians. DWR continues to work diligently to implement protective measures to minimize the spread of this invasive species, prevent the fouling of equipment and maintain operational capacity. For specific questions about DWR’s response, please contact Maggie Macias, DWR Information Officer at (916) 902-7405. For questions regarding CDFW’s response, please contact CDFW’s hotline at (866) 440-9530.

Contra Loma Reservoir

October 7, 2025 – juvenile mussels were discovered on a settlement plate in Contra Loma Reservoir, Contra Costa County. The reservoir is part of the Central Valley Project and receives water from the Delta. The mussels were genetically confirmed as golden mussel by PCR analysis and DNA sequencing.