Residential and commercial areas below hillsides charred by the Thomas fire are facing a new threat of potentially “catastrophic” flooding, if not from the first mild storm of 2018 that rolled in Wednesday then from future storms that could be more potent, according to reports from county officials.

Any floodwaters that flow before fire cleanup is completed could also contain a “toxic soup” of hazardous wastes picked up by runoff through damaged and destroyed structures within the burned areas, officials said Wednesday.

In an effort to prevent pollution from and exposure to household hazardous wastes, the county Board of Supervisors, meeting in Santa Barbara, unanimously reratified the declaration of a local health emergency initially approved Dec. 21, and the board plans to do it again at its Jan. 9 meeting.

The declaration prevents the removal of fire debris without a hazardous materials inspection conducted by county officials or personnel from the state Department of Toxic Substances Control or U.S. Environmental Protection Agency, Susan Klein-Rothschild, deputy director of the Public Health Department’s Community Health Division, said in a report to supervisors.

It applies to incorporated cities as well as the unincorporated area of the county, according to the report.

But an immediate concern for county officials is the potential for flooding below the burned watershed areas along the hillsides north of Santa Barbara, Montecito and Carpinteria, even though the current storm is forecast to drop only 0.01 to 0.10 of an inch of rain in the mountain areas, according to the National Weather Service office in Oxnard.

Rob Lewin, director of the Office of Emergency Management, said contingency plans are already being implemented, which includes issuing flash flooding alerts that may be different from the evacuation warnings issued as the Thomas fire burned westward along the hillsides.

“Evacuation may be the last thing we want some people to do because it may put them in harm’s way,” Lewin said.

Although fire damage to the watersheds and the potential for flooding is being assessed by the federal Burn Area Emergency Response team and state Watershed Emergency Response Team, the county has identified areas at risk of flash flooding and heavy debris flows.

“Because of the time of year we’re in, we could not wait for (their) full report,” Lewin said.

He and Tom Fayram, deputy director of water resources for the Public Works Department, showed images of flooding that took place following the 1964 Coyote fire and 1971 Romero fire and in 1995 when there had been no recent fire.

They also showed photos of how those areas have been developed and what they look like today as well as gravity-induced dirt and rock slides they found in a tour of at-risk areas Tuesday.

“Just one rock could close the road,” Lewin said.

Fayram said as soon as fire officials gave the OK, county crews started clearing debris from drainage basins to reduce obstructions and maximize holding capacity, and he expected all of the basins to be cleared by the end of this week.

The county also has posted an interactive map on its website that will allow residents to plug in their addresses to see where they are located and which of four kinds of risks they face — within the burn area where slides are likely, in a buffer zone that could be impacted by slides and flooding, in water courses that will become debris flows and within the 500-year flood zone, which is much larger than previously delineated.

“When you have a burn scar this large, there can be a lot of water flooding down into that flood zone,” Lewin said.

The enlarged flood zone of the map dismayed 1st District Supervisor Das Williams.

“This will be a shock to some property owners who were not in the 100-year flood plain and have not bought flood insurance,” Williams said.

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Fayram agreed the fire “is a game changer.”

“Channels can be completely filled with debris,” he said, adding that flood analysis doesn’t take debris into account, so the county’s determination of the hazard zone is much wider. “The upper watershed is all 100-percent burned.”

Lewin said the hazard map and contingency plans are not only based on the Thomas fire but, also, take into consideration burn damage from the recent Alamo, Rey, Sherpa and Whittier fires.

“If we had taken some steps beforehand, we wouldn’t have almost 300,000 acres to deal with,” 4th District Supervisor Peter Adam said, speaking remotely from the Santa Maria hearing room.

He said residents are talking about reviving the controlled burn program “with good reason” and if a predicted atmospheric river of moisture flows into the area off the Pacific Ocean, the county could experience “a catastrophic event.”

In the meantime, although the county has had difficulty contacting property owners, officials are moving forward as fast as possible on inspecting destroyed and damaged structures to assess their levels of household hazardous waste — paints, solvents, insecticides, herbicides, motor oil and other substances — and more toxic materials like asbestos.

Public Health Director Van Do-Reynoso said once an assessment has been made, the property owner can apply for a county permit to properly remove those substances or work with the county, federal EPA or state Department of Toxic Substances Control on their removal.

Board Chairwoman and 3rd District Supervisor Joan Hartmann asked if flooding could release toxic chemicals that hadn’t been cleaned up.

Larry Fay, director of Environmental Health Services, said that would likely be the case, and Lewin said the county plans to identify the hazardous materials sites that have been registered.

“It is a real concern,” he said. “There can be kind of a ‘soup’ created as the materials mix together."