State grant renews invasive quagga mussel prevention program at Lake Mendocino

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The Sonoma County Water Agency’s watercraft inspection program at Lake Mendocino will continue for another two years, thanks to $400,000 in state grant funding that went into effect on Sept. 16. The California State Parks Division of Boating and Waterways grant will fund the program to keep invasive quagga and zebra mussels from being introduced to Lake Mendocino until Sept. 15, 2026.

Quagga and zebra mussels are an invasive mussel which, if introduced into a waterway, can devastate the natural environment, clog water and flood protection infrastructure, and cost millions of dollars in maintenance. Mussels are transported between waterways by watercraft, primarily recreational boats.

Sonoma Water self-funded infestation prevention efforts at both Lake Mendocino and Lake Sonoma beginning in 2012, and in 2020 was first able to successfully obtain funds from the Division of Boating and Waterways to support these efforts. In 2024 the Division of Boating and Waterways awarded Sonoma Water a $400,000 grant supporting two more years of the program at Lake Mendocino.

"This grant is crucial for protecting Lake Mendocino's ecosystem and water supply infrastructure," said David Rabbitt, Chair of Sonoma Water’s Board of Directors. "The inspection program has proven to prevent potential infestations, which demonstrates its effectiveness. Thanks to the Division of Boating and Waterways and this continued funding, we can ensure that our lakes remain free from destructive invasive mussels, safeguarding regional natural resources and water supply systems for years to come.

In 2018, a mussel-sniffing canine inspector with the program discovered a boat infested with quagga mussels before it was able to launch in Lake Mendocino. A similar situation was averted again at Lake Sonoma in 2020 by a human screener. Trained mussel-sniffing dogs can detect the mussels even in their microscopic larval stages.

The current mussel inspection program at Lake Mendocino consists of visual and canine inspections of vessels planning to launch into the waterway. Mussel inspections are performed to thoroughly investigate a vessel for any signs of the invasive dreissenid mussels (quagga and zebra). The inspections are required by Lake Mendocino, and are offered daily from 7 a.m. - 3 p.m. The requirements include any vessel that is intended to go in the lake, including stand-up paddleboards, kayaks and canoes.

During the inspection process, a mussel screener will ask watercraft users where their last launch was, as well as whether they have launched their boat in Southern California, or out of state in the last 30 days. Adult mussels can live out of water for a week or more depending on environmental conditions after attaching to a surface. Dreissenid mussels have spread into more than 30 states, including California, the closest of which to Lake Mendocino is the San Justo Reservoir in San Benito County. Another employee, dog or human, will inspect the watercraft for mussels in all their favorite hiding places, such as the motor, or the hull of the boat. Inspections typically last less than two minutes.

The best tip to avoid picking up quagga or zebra mussels on a watercraft is to avoid waterways where they have been detected. Stay up to date on which California water bodies are infested by checking the California Department of Fish and Wildlife website routinely before taking your watercraft anywhere. If a waterbody in Northern California were to become infested with the dreissenid mussels, there is a good chance that lake would become closed indefinitely to recreation to prevent further spread to surrounding lakes. Once established, the mussels are extremely difficult to remove. Closing the lake enables experts to attempt to remove the infestation and prevent further exposure to other lakes.

Funding of this project has been provided in full or in part through an agreement with the California State Parks Division of Boating and Waterways. The contents of this release do not necessarily reflect the views and policies of the Division of Boating and Waterways, nor does mention of trade names or commercial products constitute endorsement or recommendation of their use.

For more information about the invasive mussel prevention program visit dontmoveamussel.com.

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Media Contact
Stuart Tiffen
Sonoma Water Communications
stuart.tiffen@scwa.ca.gov
707-322-1223