Smaller speedier boats run back in from the north jetty as a larger sport fisherman nears his turning point to head out the inlet and offshore, Thursday April 10, 2025, at Ponce Inlet.
Folsom, California – Boaters launching into two popular Northern California lakes will now face mandatory inspections and a 30-day quarantine in a bid to halt the spread of a rapidly advancing invasive species: the golden mussel.
Effective April 14, all trailered and motorized vessels entering Folsom Lake and Lake Clementine — located northeast of Sacramento — are subject to the new protocols. The measures come after golden mussels (Limnoperna fortunei) were discovered in October 2024 at the Port of Stockton, less than 100 miles from the two lakes. This marks the first known appearance of the invasive species in North America.
Originally from Southeast Asia, the dime-sized golden mussels pose a serious threat to California’s aquatic ecosystems and infrastructure. According to the California Department of Fish and Wildlife, the mussels consume massive amounts of microscopic plant and animal life, displacing native species and sport fish. They also pose a critical risk to municipal water systems, agriculture, and power plants, as they can rapidly multiply and clog water intakes and fish screens.
The mussels are also known to attach to boat hulls, engines, and hard surfaces, making boats major carriers of the species between water bodies.
“California State Parks is working with the U.S. Bureau of Reclamation and numerous state agencies to take critical steps to prevent golden mussels from infesting Folsom Lake and Lake Clementine,” said Mike Howard, Superintendent of Folsom Lake State Recreation Area. “We thank boaters for their understanding as we implement the new procedures and are working to make the inspection processes as efficient as possible.”
Under the new rules, vessels will be inspected on-site at all open boat launch facilities. If they pass, they’ll be quarantined for 30 days, during which a tamper-proof seal will be applied. Once cleared, vessel information is recorded in the Watercraft Inspection Database (WID) for verification.
Officials warn that an infestation at Folsom Lake — a reservoir crucial to regional hydropower and water supply — could be devastating.
The golden mussels have already been spotted further downstream in Turner Cut near Stockton. They were likely introduced via a ship from an international port, officials said.
For now, California’s preventative approach avoids full lake closures — but the threat remains urgent.
