Design work continues on new span to replace 85-year-old bridge over Sonoma Creek

Sonoma County supervisors received much flak two years ago from preservationists when they voted to scrap and replace the aging Watmaugh Bridge outside Sonoma.

County officials were concerned the steel-truss bridge was a public safety hazard and could collapse in an earthquake or major flood because of erosion around the piers that support it. But they will have to wait more than a year before it will be replaced with a new one.

The project remains in the design phase, said Tom O’Kane, deputy director of the county Transportation and Public Works Department. Construction isn’t expected to start until the summer of 2016, he said.

“It’s moving along,” O’Kane said, about the project, given the go-ahead by the Board of Supervisors after a debate with preservationists that began in 2009. Since the project is partially funded by federal dollars, the county has had many stringent requirements to meet, O’Kane said.

Designers also are dealing with an environmentally sensitive area. The bridge was built 85 years ago over Sonoma Creek.

“Sonoma Creek is so sensitive. There are multiple hurdles we have to overcome,” O’Kane said.

For example, he said they have to figure out what to do about freshwater shrimp found in pools below the span.

“We’re not supposed to touch them,” explained O’Kane. He voiced hope the large storm that dowsed the county last week would help with the relocation effort, sending the shrimp down into San Pablo Pay.

The bridge replacement, estimated to cost about $4 million, cannot come soon enough for Gary Helfrich, executive director of the Sonoma County Bicycle Coalition.

The narrow, two-lane structure has long been considered a dangerous passage for both cyclists and pedestrians, Helfrich said. There are no bike lanes and the road curves as it approaches both ends of the bridge, which he said makes it difficult for cyclists and pedestrians to see approaching traffic.

“There’s no place to go,” Helfrich said. “You’re up against steel on one side and traffic on the other.”

Cyclists often prefer to take surrounding roads, but they tend to be more congested and have higher speed limits, such as Highway 12, Helfrich added.

“(Highway) 12 is like riding on the freeway,” he said. “I’m really glad that Public Works is finally fixing these bridges that are in bad shape. It’s not only good for motorists, it’s good for cyclists .?.?. You don’t want to go over a bridge wondering, ‘am I going to make it to the other side?’?”

About 4,000 vehicles daily cross over Watmaugh Bridge, which links Arnold Drive to Highway 12 leading into downtown Sonoma. The project calls for putting in new bike and pedestrian lanes on the replacement bridge, as well as realigning the road. The county also plans to incorporate into the new bridge the existing span’s key visual feature - the steel trusses.

Preservationists and some neighbors wanted the bridge retrofitted instead of replaced and complained that the county never seriously studied that option. Some also worried a new span would take away from the Sonoma Valley’s ambiance.

The bridge was designated a county historic landmark in 1981 after preservationists saved it from being torn down.

O’Kane said it would have cost the county the same amount to retrofit the bridge, but it wouldn’t have had as long of a lifespan. It also would never have received an approval for federal funding, he added.

The existing span has one of the lowest ratings for structural safety of any in Sonoma County, which has more than 300 bridges, according to O’Kane. But residents shouldn’t be concerned. He said state and local officials continue to closely monitor the Watmaugh Bridge. County inspectors checked the bridge after a magnitude-6.0 earthquake shook the region Aug. 24. They found no significant damage.

“That was the first one (bridge) we checked,” O’Kane said. “We had someone out there that morning.”

While it may seem a long time to wait for the new span, O’Kane said other bridges in the county have taken longer to replace, including one on Porter Creek Road. “It took 21 years to get that one under construction.”

You can reach Staff Writer Eloísa Ruano González at 521-5458 or eloisa.gonzalez@pressdemocrat.com. On Twitter @eloisanews.