Napa supervisors signal intent to authorize boat inspections at Lake Berryessa to keep invasive mussels out

The Napa County Board of Supervisors on Tuesday voted unanimously to express its intent to adopt an ordinance that would add chapter 6.02 to the Napa County code authorizing inspections of watercraft for invasive mussels at Lake Berryessa.

County counsel Tom Zalley opened the public hearing by framing the action as a preventative measure: “Lake Berryessa is clean right now. We don't want those mussels in there,” he told the board before turning the presentation over to county and conservation staff.

The board's action follows a presentation from Martin Peralez, a PhD aquatic ecologist with the Napa County Resource Conservation District, who described the golden mussel as a highly invasive freshwater species recently detected in California's Delta. Peralez warned the species is prolific and mobile: “They can survive out of water for weeks,” he said, and described both adult mussel fouling of hulls and microscopic free‑swimming larvae — known as veligers — that can travel inside bilges, live wells and water on boats.

Why it matters: Peralez and county counsel…