Friday, 17 July 2026, 6:57
The California Department of Fish and Wildlife (CDFW) confirmed in late June that golden mussels (Limnoperna fortunei) have been detected in the Port of West Sacramento and the Sacramento River Deep Water Ship Channel. This marks the northernmost sighting of the invasive species since it was first found in North America in 2024, putting Lake Tahoe at heightened risk.
Golden mussels form dense colonies that encrust pipes, pumps, and gates. In the San Joaquin River Delta, they have already driven up infrastructure costs. Stockton city leaders declared a local emergency after mussels clogged a drinking water pump station, and Assemblymember Rhodesia Ransom announced $6 million in state funding for maintenance and prevention. Unlike quagga and zebra mussels, golden mussels tolerate a wider range of salinity and temperatures, making them harder to control.
Yolo County is considering declaring a state of emergency, following Sacramento County, which declared one last month. The spread threatens not only water infrastructure but also native fish and wildlife. Krysten Kellum, a CDFW spokesperson, noted that golden mussels can outcompete native species and contribute to harmful algal blooms. The species likely reached West Sacramento via boats moving through the ship channel from the Delta. Yolo County spokesperson Will Arnold said the county is working with West Sacramento and the port to coordinate next steps, and is looking to the state Fish and Wildlife Department for expertise. California’s recently adopted budget includes $6 million of one-time funding and $1.5 million of ongoing funding to help address the problem, which will be used to set up decontamination control sites in the Delta.
The Tahoe Regional Planning Agency (TRPA) has intercepted three boats with golden mussels since May 2025. Jeff Cowen, TRPA's public information officer, said the detection near Sacramento is concerning but that inspection protocols developed in 2025 are designed to reduce risk. Lake Tahoe uses mandatory boat inspections and the Clean, Drain, Dry program for all watercraft. With early spring and warm temperatures boosting tourist activity, the risk of introduction is elevated. Last month, six boaters in Lake Tahoe were caught attempting to illegally launch without proper inspections, and officials found tampered inspection seals. The timing adds to the concern: Tahoe is already in the height of boating season. The Tribune reported that the Tahoe Regional Planning Agency had earlier stopped boats carrying golden mussels — one in May of last year and two more in June. A Lake Tahoe infestation would be more than a boating nuisance. Golden mussels can harm biodiversity, interfere with water infrastructure, and raise maintenance expenses in a lake celebrated for both its ecological condition and exceptional clarity. These mussels have also caused issues in Michigan, where attorneys challenged weakened EPA ballast rules that could cause further spread of invasive animals like golden mussels and zebra mussels in the Great Lakes. Protecting public water systems could require added spending from government agencies, with the concern that these costs could ultimately land on residents, visitors, and local businesses. Because Tahoe depends so heavily on tourism, any decline in the lake's condition could also strain outdoor recreation and local employment. Their spread would also complicate broader freshwater protection work. Time and money that might otherwise go toward restoration or water management could instead be redirected to emergency measures and invasive-species prevention.
Golden mussels are native to China and were first detected in North America in 2024 in the Port of Stockton. They have since spread through the Sacramento-San Joaquin Delta. Unlike other invasive mussels, they can survive in a broader range of conditions, making eradication nearly impossible once established. Control methods like hot water treatments and manual scraping have proven only temporary. Kellum said that even if those efforts work in the short term, the mussels come back. The only real option has been trying to slow down the pest’s spread by making boaters and recreators aware of the risk. Golden mussels cannot swim, but they can survive by attaching themselves to boats, which transport them to new bodies of water. To avoid that, boaters should be prepared to clean, drain and dry their equipment between each use. In some places, including Lake Tahoe and Lake Berryessa, owners will need to have their boats inspected before being allowed to launch.
While many waterways are ramping up inspections, the California Department of Water Resources (DWR) has rolled back boat inspections at Lake Oroville, the state’s largest reservoir, as of April 2025. This decision comes despite the mounting threat from golden mussels, which have spread over 500 miles in under two years, from the San Joaquin Delta to West Sacramento and San Diego. DWR and CDFW have launched a statewide campaign to stop the invaders, but at Lake Oroville, officials are betting on climate and fluctuating reservoir levels to keep the mussels from gaining a foothold. A new assessment showed “a lower risk of golden mussel establishment than was originally anticipated,” according to an April news release. The colder climate means the mussels will likely only survive in the top 60 feet of the lake, which currently measures 876 feet deep. Officials believe the varying water levels will dry out and kill the mussels before they can establish permanently. However, advocates and experts argue that it’s unknown whether Lake Oroville will escape infestation forever. Laura Patten, natural resource director of Keep Tahoe Blue, said the decision underscores a big problem: the state “lacks consistent statewide protections against golden mussels.” She called the approach a “patchwork” that undermines efforts at Lake Tahoe and creates vulnerabilities across the system. “Golden mussels don’t care which agency actually manages a reservoir. These things are spreading like wildfire right now,” Patten told SFGATE. “And our concern is that once they get in, invasive mussels do have the potential to really destroy an ecosystem in a place like Lake Tahoe and we can’t fully protect ourselves, as the protections elsewhere are inconsistent.”
The discovery of golden mussels near Sacramento demands immediate action. Boaters and recreators must clean, drain, and dry equipment between uses to prevent further spread. Report suspected mussels to CDFW's Invasive Species Program with location and photos. For Lake Tahoe, mandatory inspections are critical. The outcome of AB1772 will determine future funding and coordination. Lawmakers in Sacramento are now weighing AB1772, which would bolster California's approach to aquatic invasive species by pinpointing funding sources, creating a contamination database for water managers, and establishing a statewide vessel-decontamination standard. For Tahoe itself, officials are still emphasizing prevention above all else. The basin's Clean, Drain, Dry campaign tells people to inspect boats and gear — from kayaks and paddles to life vests — whenever they leave the water. Motorized watercraft must also go through inspections and, if needed, decontamination. Before taking equipment from one water body to another, the region urges people to inspect it carefully, comply with screening rules, and report suspected golden mussels to the California Department of Fish and Wildlife's Invasive Species Program with a clear photo and location information. Anyone planning to launch at Tahoe can visit TahoeBoatInspections.com to book an appointment and check the current requirements before going. The CDFW provides a resource for people to report sightings of animals that look like golden mussels, encouraging people to report where they saw it and a photo of the organism by emailing them at [email protected] or calling (866) 440-9530. "We work with scientists and partners through the Aquatic Invasive Species Coordinating Committee to regularly evaluate the program and apply new information so that it maximizes protection for Lake Tahoe and the waters of the region, while ensuring everyone can enjoy all that Tahoe offers," Cowen said.
