DNA analysis confirmed this week that stowaway shellfish intercepted at the Lake Mendocino boat ramp early this month were invasive quagga mussels, as initially feared.
The finding by state Fish and Wildlife personnel validates just how close the region came to confronting a destructive scourge. Infestation by the nonnative bivalve could have had profound implications for wildlife and recreation in the lake, as well as water-supply infrastructure serving more than 600,000 residents in Sonoma and northern Marin counties, officials said.
But for the moment, it appears the crisis was averted, thanks to a sweet-faced, blond Labrador named Noah. The mussel-sniffing dog and his handler have been showered with gratitude from recreational boaters since they detected tiny quagga mussels aboard a vessel about to be launched into Lake Mendocino on June 2.
“It’s been amazing, the community response,” said Brad Sherwood, a spokesman for the Sonoma County Water Agency, which contracts with Central Valley-based Mussel Dogs for weekend boat inspections at both lakes Sonoma and Mendocino. “The mussel inspection team has gotten nothing but praise and support from the community.”
Fish and Wildlife personnel still are trying to determine where the vessel, owned by a Marin County man, had been used before Lake Mendocino, and if any other water bodies may inadvertently have been exposed, said Martha Volkoff, environmental program manager for the agency’s habitat conservation planning branch.
The boat was on loan to a group of fathers planning to camp and explore the lake with their daughters when it was intercepted at the launch and escorted to a sanitation station in Lake County, officials said.
Quagga mussels, like their cousins, zebra mussels, breed at a high rate and exist as juveniles in a larval state that spreads readily in water. The mussels also can survive for days outside water, enabling them to hitchhike on unwashed or undried boats to otherwise uninfected waters.
Once introduced, they are virtually impossible to get rid of and quickly out-compete and overcome other aquatic wildlife. Infestation typically leads to infrastructure damage as well, including clogged water pipes, tunnels and turbines.
Asked Thursday to size up the potential threat of exposure, Nicholas Malasavage, chief of operations and readiness for the Army Corps of Engineers’ San Francisco District, which oversees lakes Mendocino and Sonoma, replied, “I have a tough time finding words.”
“There is the threat to environmental security, and then there is the threat to just infrastructure and the gates at the dam, the boat ramp itself,” Malasavage said. “But it is hard to capture that in words, which kind of speaks to the heightened urgency to keep it from happening in the first place.”
The freshwater mussels are native to eastern Europe but have spread across the U.S., beginning around 1989 with their introduction to the Great Lakes, reportedly through ballast water. They’ve caused catastrophic and expensive damage at places like the Great Lakes and Lake Mead and eventually found their way to California, where they were first discovered in 2007.
Since then, quagga or zebra mussels have been confirmed in 43 waterways around the state, mostly in Southern California. The northernmost discovery was in San Benito County.
But despite the enormity of a potential infestation and a $600,000 state grant, the Army Corps is still working out permanent boat inspection plans for the two local reservoirs. That’s in part because of incompatible administrative requirements between state and federal agencies and a need to balance investment in direct inspection, outreach and education, Malasavage said.