Sonoma County transit planners have gone back to their original plan to replace a historic steel truss bridge near Sonoma following another contentious hearing over the span's fate.

County officials had proposed erecting a new span adjacent to Watmaugh Road Bridge in an effort to appease those who want the bridge retrofitted and preserved.

But following another frosty reception at last week's county Landmarks Commission meeting, county planners have reversed course again and are now proposing to replace the span.

"At this point, we will pursue our original plan for the replacement of the structure to include all the caveats that have been discussed, including retention of the trusses and reducing the overall width from the original," said Tom O'Kane, the county deputy director of public works.

The Watmaugh bridge was constructed in 1929 to span Sonoma Creek and connect what is today Arnold Drive with Highway 12 leading into Sonoma. The bridge is one of two steel truss bridges in Sonoma Valley and in 1981 was designated as a county historic landmark after preservationists saved it from being torn down.

County officials say the bridge is at risk of collapse during an earthquake or major flood because of erosion around the piers that support it. But preservationists contend that officials are inflating the risks and that the span can be brought to safety standards without having to replace it.

The county's alternate plan was met with resistance from landowners adjacent to the proposed new span. They told commissioners at last Tuesday's meeting that a realigned Watmaugh Road would encroach too far onto their property and result in the destruction of numerous landmark trees.

"There was an overall agreement by the commissioners that the bridge should continue to be used by vehicular traffic and the best way to accomplish this is to retrofit the bridge," said Nancy Simpson, Sonoma Valley's designate to the county Landmarks Commission. "There was also an overwhelming consensus by the community and the residents that the parallel bridge would never be an option in that location."

County transit planners have said it would cost as much to retrofit the bridge as it would to replace it, and that the funds that are available to do the work are tied specifically to building a new span.

The Landmarks Commission has the authority to review changes to the bridge under a 1998 Board of Supervisors resolution that designated Watmaugh and 11 other bridges part of a county-wide historic bridges district.

O'Kane said his staff will return to the commission later this summer to formally present the county's plans to replace the bridge. The ultimate decision rests with county supervisors.