The future of an aging steel-truss bridge near Sonoma is set to be decided Tuesday by the Sonoma County Board of Supervisors.

The board is scheduled to cast a straw vote on a proposal to replace the 83-year-old Watmaugh Bridge spanning Sonoma Creek and linking Arnold Drive with Highway 12.

A tug-of-war over the bridge's fate has been going on for the past two and a half years.

County officials say the existing span is at risk of collapse during an earthquake or a major flood because of erosion around the piers that support it.

But preservationists contend the risks have been inflated and have lobbied instead for rehabilitation of the bridge.

The county Landmarks Commission also recommended that a replacement bridge not be built because of the potential effects on the span's historical character and because other alternatives had not been explored.

The county has downscaled the proposed replacement bridge, reducing its width from 40 feet to 32 feet. The proposal also calls for trusses from the existing bridge to be incorporated as ornamental features.

Tuesday's 2:10 p.m. hearing will also focus on an environmental impact report for the project.

A straw vote approving the project would be finalized at the board's Dec. 11 meeting.

You can reach Staff Writer Brett Wilkison at 521-5295 or brett.