Over the opposition of preservationists, the Sonoma County Board of Supervisors on Tuesday ended nearly three years of debate on the fate of Watmaugh Bridge outside of Sonoma, voting to scrap the aging span and replace it with a new one.

The 83-year-old steel-truss structure crosses Sonoma Creek and links Arnold Drive with Highway 12. County and state officials have said it is a public safety hazard, at risk of collapse during an earthquake or major flood because of erosion around the piers that support it.

But preservationists and some neighbors had fought to have the bridge retrofitted instead. They've said the county never seriously studied that option. On Tuesday, before the board vote, both sides went at it again.

Bridge preservation advocates said there was state money to retrofit the span, if only the county would shelve its plan and seek out those funds. "The citizens do not feel they have been heard or that the facts have been paid attention to," said bridge advocate Johanna Patri.

Her comments and others by bridge supporters drew a sharp and exasperated response from Supervisor Valerie Brown, who represents the area. Caltrans was not interested in retrofitting the structure, she said, no matter how many times they county asked them. The county has compromised, she added, by incorporating the existing bridge's key features, the steel trusses, as ornamental elements of the new bridge.

"Folks I know you're not happy with where this is going, but you cannot say you have not been heard. You can say we don't agree with you. You can say we're putting public safety over historic preservation," she said. "But the day I say public safety does not come first for me is a very sad day and one where I can't sleep in bed that night."

The four other supervisors echoed Brown, each saying the county's study had been sufficient and that the risks were high enough to demand immediate action.

Gary Helfrich, executive director of the Sonoma County Bicycle Coalition, supported the decision, saying the new span would give safe passage to cyclists and pedestrians. The current narrow structure does not, he said.

Tom O'Kane, interim co-director of the county's public works department, said design work on the new bridge would be completed by this time next year, with construction starting thereafter. Total costs are estimated at $4 million to $5 million.

Rose Zoia, an attorney representing a group of bridge preservationists, would not discuss their next step but said it could involve a legal challenge. "We have to close ranks and discuss that," she said.

The board is set to finalize its vote at the Dec. 11th meeting.

You can reach Staff Writer Brett Wilkison at 521-5295 or brett.wilkison@pressdemocrat.com.