Know your risk: Flood experts offer advice in case disaster hits

Apr. 22—Southwest Bakersfield homeowner Joe Ortega worries, not just for his household but for everyone in the city, what would happen if sudden warming were to accelerate melting of this year's unprecedented snowpack in the southern Sierra Nevada.

What parts of town might flood, he wonders, if so much water flowed into Isabella Lake that authorities had to release a dangerous torrent toward Bakersfield? Would people downstream be prepared for a disaster observers say looms as a possibility?

"That's what people have to be ready for, because Mother Nature's in charge," Ortega said by email.

No one's sure what would happen in that scenario. Even so, federal authorities have a good idea what areas seem to be at highest risk if water levels were to rise, and anyone with a computer and wifi can fairly easily find that information for free.

Interactive maps are posted online at websites such as msc.fema.gov and riskfactor.com allowing users to see what parts of town — and specific addresses — are deemed to face the greatest threat in the event of a one-in-100-years or one-in-500-years flood event. The sites are among many online resources providing information about chances of suffering damage and ways of possibly reducing them.

Risk Factor, a data-driven tool run by a nonprofit advocating climate action, estimates 1,538 properties in Bakersfield, or 18 percent of the city's inventory, have a greater than 1-in-4 chance of being severely affected by flooding in the next 30 years.

The Federal Emergency Management Agency's site classifies a small minority of residential and commercial properties, most of them near the Kern River, as having a 1 percent chance of flooding in any given year. Many more buildings are shown as having reduced flood risk because they are protected by a levee.

But people whose job it is to prepare for or deal with floods warn that the unexpected happens a lot in their line of work. FEMA spokesman Frank Mansell noted 40 percent of claims through the National Flood Insurance Program are paid outside flood zones.

"That means that Mother Nature doesn't read the maps," he said.

George Booth, Sacramento area-based executive director of the Floodplain Management Association, said even FEMA maps don't tell the whole story, and that levees and dams "can only do so much." Concerned about the possibility of a warm atmospheric river in the southern Sierra, he suggested people look into flood insurance because "you can always cancel it."

Flood plain managers say residents can take a number of steps to lower their exposure to being ruined by a flood. These range from physically moving important documents and irreplaceables to higher ground to setting up a family plan for staying in contact, maybe altering the building itself or the area around it.

"The thing to do is everybody needs to know their risks," Booth said.

Almost two weeks ago, the state Department of Water Resources estimated snow in the Isabella Lake watershed at 429 percent of normal, or 1.83 million acre-feet of water. Based on historical patterns, they projected next month's snowmelt will jump 69 percent with the onset of greater sunlight and seasonal warmth.

That prompted the U.S. Army Corps of Engineers to ask Kern River Watermaster Mark Mulkay to gradually increase the flow out of Isabella Dam to 7,000 cubic feet per second from the roughly 5,400 cfs rate at which it has flowed recently.

Some involved in the conversation, including Mulkay, who called the current scenario the worst in 40 years, said an unseasonable rise in temperatures could mean water would have to be released even faster, which could put downstream infrastructure in danger and possibly flood vulnerable parts of Bakersfield.

Government has raised no alarm and generally remains guarded about the outlook.

County officials in three different departments didn't respond to requests for comment. The Corps of Engineers declined to disclose or discuss flood-risk projections.

The California Governor's Office of Emergency Services did not respond to questions about an agency staff member who called last week to verify personal contact information, saying she was reaching out to Bakersfield residents in preparation for the possibility of flooding from snowmelt in the southern Sierra.

The city of Bakersfield provided a written response to questions, saying it would use various channels of communication to keep residents informed of flood impacts and steps taken to address them. For now, it is diverting flows to groundwater recharge basins, clearing debris to prevent future blockage and continuing to perform routine inspections along the city's levees, a city spokesman noted.

As for what people should do to prepare, a spokesman stated, "At this time, the city, its Water Resources Department and Public Works Department do not anticipate major impacts to the city or its residents as a result of the increased flows through the river." He emphasized the city is working with the Corps of Engineers, the state DWR and area water agencies to monitor snowpack and "mitigate any potential impacts."

Executive Director Chad Berginnis of the Association of State Flood Plain Managers noted the most damaging flood scenario in the country, called the Arkstorm, would put every city in the valley underwater. Even far short of that, major flooding is expected to hit the Central Valley every 200 years.

"It is a real threat," he said. "It is a recurring threat."

Having seen too many people be surprised by flooding they had all but ruled out, Berginnis advised Bakersfield-area residents to take steps to protect themselves and their property.

"Try to avoid the mindset that because it's never flooded here, it will not flood in the future," he said.