Efforts to stabilize Sonoma County’s fire-scarred landscape against winter rains gained urgency Wednesday as a moisture-laden storm arrived in the region, raising the risk of mudslides, flash flooding and fallen trees.
The massive wildfires that swept through Wine Country in October torched nearly 140 squares miles of Sonoma County, baring huge patches of remote landscape and reducing whole neighborhoods to ash and rubble.
The fires were still burning when work crews began spraying some burned slopes with a slurry of seed and mulch to promote rapid vegetation growth. Elsewhere, straw-filled erosion-control wattles, sandbags and other barriers have been deployed to try to stabilize hillsides and contain runoff that may be contaminated by burned materials or carry sediment.
But much of the burned-over area remains at risk of debris or mudslides, particularly in the perimeter of the Tubbs fire, where the severity of the fire was most pronounced overall, according to early assessments.
Each fire footprint has steep, isolated areas where the threat of sliding rates high, with the largest such area in and around Hood Mountain Regional Park near Pythian Road and above Highway 12, according to post-fire hazard mapping.
Sonoma County watershed recovery coordinator Cordel Stillman said first-responders contacted a few residents in the area Wednesday to ensure they were aware of the incoming storm and were prepared to take precautions, if necessary.
Santa Rosa work crews also have been working feverishly to assess and repair 23 problem spots identified in Fountaingrove, where underground drainage lines and culverts have melted in some cases, and could cause slides or sinkholes in areas of saturated soil, Assistant Santa Rosa Fire Marshal Paul Lowenthal said.
Flyers were distributed several days earlier to more than 1,200 residents and businesses in the area, encouraging them to enroll in emergency notification systems and have emergency plans in place. But any evacuation “would be very localized, specific to the actual area of concern,” Lowenthal said.
City crews were planning to patrol the area through the night, monitoring the hillsides, but “none of the locations presents a significant public safety risk,” Lowenthal said.
The atmospheric river forecast by the National Weather Service was at least expected to be shorter in duration than most, lasting only until into the predawn hours today, followed mostly by light, scattered showers, meteorologists said.
Close to 2 inches of rain were expected in most urban areas by this morning, with 3 inches or more at higher elevations, including some of the mountainous terrain where recent wildfires stripped the vegetation from large ridgeline swaths, according to National Weather Service meteorologist Scott Rowe.
The weather service predicted bursts of rain descending at a rate of a half-inch per hour, potentially loosening exposed slopes and contributing to rapid accumulation of runoff. A flash flood watch was issued, but officials did not anticipate having to alert or scramble the public for any reason, Stillman said.
Cal Fire spokeswoman Suzanne Brady said she did not foresee serious ramifications.
“We just want people to keep their head on a swivel, be aware of their surroundings, looking around for what’s going on, and if they see something wrong, report it,” Brady said.
Out of caution, emergency plans were laid late Wednesday in the event of unexpected or isolated problems that put members of the public at risk, they said.