Repairs to storm-damaged stretch of Highway 116 could take a year, Caltrans says

Repairs to storm-damaged Highway 116, a key thoroughfare along the lower Russian River in western Sonoma County, could take a year to complete once the work begins, with travel limited to one direction at a time until then, Caltrans officials said Tuesday.

That word came a day after the rain-saturated soil beneath a stretch of the highway just west of Monte Rio gave way about 4 p.m. Monday, spilling into the swollen Russian River.

The earth, likely loosened by the surging waterway and runoff from the recent storms, dragged down some trees, a portion of the guardrail and 75-100 linear feet of the road, eating into the eastbound lane.

The washout is expected to grow as runoff continues to pour down the hills that flank the highway’s westbound lane leading out of Monte Rio, Caltrans spokesperson Jeff Weiss said Tuesday. Between Dec. 31 and Monday night, storms have dropped about 6 inches of rain around Monte Rio and about 10 inches in the nearby hills of Austin Creek State Recreation Area.

The lower Russian River jumped by more than 20 feet over that same period, cresting in Guerneville on Tuesday afternoon at more than 30 feet, or just two feet shy of flood stage.

The washout led Caltrans on Monday night to immediately close the damaged eastbound lane of Highway 116 near Monte Cristo Avenue, implementing one-way traffic controls that are now expected to continue for many months.

On Tuesday afternoon, multiple Caltrans workers were at the site, keeping an eye on washout and directing motorists away from the eastbound lane, which was also lined with orange cones.

“We’re doing our best to keep the road in place, but there’s very little we can do right now, except for put it under one-way traffic control and keep people on the westbound lane,” Weiss said.

Cazadero resident Karen Harris drove past the damaged road segment both Monday night and Tuesday morning. As longtime resident in the storm-battered area, it was not an unfamiliar sight.

“Every year we lose a chunk of the road somewhere, whether it is (Highway) 116 or Highway 1,” Harris said.

“The river just erodes things. You can’t stop this wonderful force of nature,” she said Tuesday, staring out at the river from a park near Monte Rio Beach.

Highway 116 is a main route that connects the Highway 101 corridor and Sebastopol to west county communities including Forestville, Guerneville and Monte Rio. From Guerneville, it is the main route west, along the river, to Monte Rio and the coast.

There are routes around it. However those alternate roads are also often impacted by flooding or storm hazards such as downed trees at this time of the year.

“(Highway 116) is a primary evacuation route and commuting road,” said Sonoma County Supervisor Lynda Hopkins, whose district includes west Sonoma County. “If it isn’t repaired before summer, it’s going to cause huge headaches for residents, local businesses and visitors.”

It also can create apprehension going into peak fire season, Hopkins said.

Caltrans did not have a timeline for when it expected to begin repairs. The work is slated to be a two-stage process that will take between eight months to one year once construction gets underway, said Weiss, the Caltrans spokesperson.

The first stage will be “shoring up” the road by building a retaining wall for support. The second stage will involve constructing a second retaining wall and drainage to ensure the road does not erode again.

Caltrans also is considering whether or not to construct a temporary retraining wall, which would be built by driving flat interlocking panels of steel into the earth.

“We have a lot of experience with these sort of repairs, so we are able to react quite quickly,” Weiss added, “But I don’t have a schedule yet.”

Caltrans is applying for emergency funds through the state to cover the project, which will likely cost millions of dollars. Weiss said he expects the request will be approved based on previous experience. Also, the project is a priority given the heavy traffic that flows through the road, especially during the busy summer months along the lower river.

Slides are not new along Highway 116 on the lower Russian River. The alignment, between a pulsing river and steep hills, makes it a hot spot for moving earth and downed trees during the winter, Weiss said.

Crews this summer finished repairing a section of the highway in Guerneville’s Montesano neighborhood that was damaged in December 2024 by a landslide. In late August, Caltrans began work on an area just east of Monte Rio that was at risk for slides, Weiss said. One-way traffic is still in place for the latter project, which is going to cost about $14 million.

Weiss said the area affected in Monday’s washout was not identified as a problem area and was more of a “surprise.”

The one-way traffic system will likely be in place throughout the construction process, with brief full closures to move in equipment, Weiss said.

That outlook, however, is dependent on the washout not getting much worse, which it could as the winter continues.

If one-way traffic holds up, Monte Rio resident Ruben Duran said he doesn’t expect much of an impact, especially during the winter.

“There’s not even a lot of campers going by right now,” Duran said, taking a break from clearing mud away from his buildings near downtown . “They’ll find another route.”

Area resident Penny Knapp said it would be a “pain in the neck,” if the portion of Highway 116 was shut down, forcing motorists to get to Guerneville via Bodega, she added.

Sonoma County is dealing with a number of other storm-caused slides and flooding, Public Infrastructure Director Johannes Hoevertsz said Tuesday. He mentioned Wohler Bridge in Forestville, Westside Road near Hacienda Bridge and Fitch Mountain Road in Healdsburg as problem areas. A lane of Harrison Grade Road outside of Sebastopol was also carried away by a slide.

Based on rough estimates, the damage is expected to cost less than $1 million, Hoevertsz said. That’s nothing, he said, compared to the $10 to $15 million required for storm repairs in past winters.

You can reach Staff Writer Madison Smalstig at madison.smalstig@pressdemocrat.com. On X (Twitter) @madi.smals.