What is the Golden Mussel and Why is it Important?
The golden mussel is a highly invasive foreign species that has recently been detected in parts of Northern and Central California, and appears to be spreading. Their color ranges from dark brown to gold, and they can reach up to 1¾ inches long. If these species are able to gain a foothold in Crowley Lake, they will cause significant damage to the area’s water ecosystem, which will negatively impact the ability of trout to thrive in Crowley Lake and its tributaries.
It is especially important that all boats entering Crowley Lake follow inspection protocols to prevent the spread of these mussels, which even if they are not visible on the outside of a boat’s hull can live for weeks or months in the bilge water.
On April 26, 2025, the San Joaquin County Board of Supervisors declared a local state of emergency regarding the spread of the Gold Mussel invasive species.
The California Department of Fish and Wildlife has prepared a Golden Mussel fact sheet.
You can report a sighting of Golden Mussels here.
Watch Crowley Fish Foundation’s Scientific Advisor Nick Buckmaster and Board Secretary Chris Leonard discuss the Golden Mussel threat in this episode entitled “California Invaders, the Golden Mussel” on Laughing Parrot Productions (December 30, 2025)
Photo: Jeb Bjerke, CDFW