Invasive golden mussels have been recently found at Lake Del Valle near Livermore, prompting park officials to enforce a 30-day quarantine on watercraft there.
The 5-mile-long lake at Del Valle Regional Park is part of the East Bay Regional Park District. Until this week, Contra Loma Reservoir in Antioch was the only waterbody in the District where golden mussels had been found, officials said Monday.
Now, boaters at Lake Del Valle are under the same rules governing Contra Loma: a 30-day quarantine before watercraft that have been on the lake are permitted at any other waterbody managed by the district.
Golden mussels originated in Asia and quickly spread through the state since first being identified in the Sacramento-San Joaquin River Delta in 2024. The mussel is a freshwater species that inhabits shallow waters and hard surfaces, impeding water flow, clogging pipes and damaging equipment while also affecting native species.
California has emphasized a “Clean, Drain, Dry” campaign for local boaters to try to stop the spread of mussels or other invasive species.
Park District staff have used tamper-proof bands placed between the watercraft and trailer when a boat leaves the lake. These bands serve as proof that the vessel hadn’t launched in other waters.
Boats that launch exclusively at Lake Del Valle and return with an intact Del Valle boat band will not be subject to the quarantine.
The Park District has used the lake-specific bands since summer 2025 in an effort to prevent the introduction of golden mussels.
Boats without a Park District boat band are subject to inspection for the presence of quagga, zebra, and golden mussels. Inspection fees are $10 for motorized vessels and $5 for car-top watercraft and inflatables. Fees partially offset the cost of the inspection program.
Other agencies that manage waterbodies elsewhere in the Bay Area and beyond may impose their own quarantine requirements, so boaters should check the websites of respective managing agencies for current rules.
More information is available on the East Bay Parks website.