County orders up emergency work as Russian River threatens Geyserville’s River Road

With each storm, the rain-swollen Russian River is washing away more of a steep, muddy bank perilously close to River Road near Geyserville, prompting Sonoma County supervisors to approve Tuesday an emergency repair estimated at $250,000.

Should the river wipe out the road, about 400 residents of Alexander Valley, a famed wine grape growing area, would be cut off from a connection to Highway 128 leading southwest to Geyserville and Highway 101.

Rebuilding the threatened stretch of River Road, including purchase of valuable vineyard property, would cost about $7 million, Transportation and Public Works Director Johannes Hoevertsz said.

“We need to move quickly,” he told the supervisors, who promptly approved the fix on an emergency basis, waiving competitive bidding.

“This is really something that happened overnight,” said Supervisor James Gore, whose district includes the Geyserville area.

Drone images from above and river-level photos confirmed a dramatic three-foot loss along the river bank during a Jan. 17 rainstorm, exposing it to further erosion. Last weekend, a lighter storm swept away another two feet.

“We’re losing ground every time it rains,” Hoevertsz said in an interview.

The trouble spot is about a mile north of Geyserville on River Road, where the river takes a sharp left bend around a 1,200-foot-wide gravel bar that pushes water up against the river’s exposed left bank.

Transportation officials have had an eye on the spot for three years, but hadn’t seen anything worrisome until the two recent storms.

An inspection on Monday revealed the exposed roots of a tree believed to be stabilizing the river bank but now appears compromised. “Erosional losses are now critically close to undermining the portion of River Road located at the top of the bank,” a staff report said.

The road is the “sole access point in and out of the area,” and its loss would cut off residential and emergency access to about 200 dwellings and numerous businesses, the report said.

A collapse of the road at night could result in vehicles plunging into the river, it said.

“Immediate action is now needed,” County Counsel Bruce Goldstein told the supervisors, justifying a vote on an unscheduled agenda item.

The proposed fix involves placement of 3,200-pound “blast mats” in an overlapping pattern along about 500 feet of the river’s northern bank. The mats are made of rubber tires chained together in pieces measuring 16 feet by 10 feet, forming a “curtain” along the bank, Hoevertsz said.

The mats will be secured by steel cables connected to steel piles driven into the ground and reinforced by concrete rails, he said.

It will take two weeks to have the materials delivered, and work on the bank will begin immediately, Hoevertsz said.

In the longer term, he said, the county should “think about managing the gravel” in the river bed, restoring the river channel to its configuration in a 1993 aerial photo, flowing relatively far from the trouble spot.

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.