U.S. Maps Show Danger of Flooding

Since this fall’s wildfires charred nearly 740,000 acres in Southern California, the risk of floods and mudslides has markedly increased, particularly in neighborhoods near foothills, streams and flood basins, according to new federal flood hazard maps released Wednesday.

The maps of the burned areas in five Southland counties pinpoint neighborhoods throughout the region that are at risk of being inundated with water, debris, sediment and mud during a heavy storm, said officials from the Federal Emergency Management Agency and the state Office of Emergency Services.

“There are no real surprises here,” said David Fukutomi, FEMA’s deputy coordinating officer for the wildfires.

The risk is greatest along tributaries and flood control channels, because a heavy storm around the charred mountains could bring down a wave of blackened branches, shrubs and dirt.

The maps show, for example, that huge swaths of neighborhoods along Arroyo Simi Creek in Simi Valley, Santa Ana Wash in San Bernardino and the San Diego River in San Diego are within the new flood hazard zones.

According to FEMA, homeowners and merchants within the zones have a 25% chance, on average, of having major flood damage within a 30-year period. Federal officials estimate that the risk of flooding will remain high for three to five years, until the mountain trees and foliage regrow.

But there was good news: Edwin Clark, a meteorologist for the National Oceanic and Atmospheric Administration, said ocean temperatures indicate that Southern California residents should expect a drier-than-normal winter this year, with the heaviest rains in January and February.

The flood hazard maps are posted on the Internet at www.capostfirefloods.net.

The maps show the flood hazard zones that existed before the fires in blue and the new, post-fire risk areas in red.

Fukutomi and other emergency officials unveiled the maps at a news conference in the Del Rosa neighborhood of San Bernardino, hit hard by the fires. A few yards behind the lectern stood the charred remains of several burned homes and, just above the neighborhoods, barren hills.

Among the neighborhoods included in the new hazard zones are dozens of blocks of middle-class homes between Sand Creek and the Twin Creek flood control basin in San Bernardino. Also in the zone is the neighborhood between Interstate 215 and Kendall Drive, south of the Devil Canyon basins.

FEMA officials note that the maps are not substitutes for maps that determine insurance rates. Fukutomi also stressed that homeowners and merchants should not rely solely on the maps to determine the flooding risks. He said property owners should gauge the threat based on the topology and history of flooding in their neighborhood.

FEMA officials also urged residents who fear that their homes are at risk of flooding to buy insurance before heavy winter rains arrive. Most flood insurance policies take effect 30 days after purchase.

Last month, the San Bernardino County Board of Supervisors voted to spend $2 million to clear burned trees and shrubs in danger of washing into nearby flood control channels and creeks.

The city of San Bernardino has bought 200,000 sandbags and 150 lengths of concrete railing to help divert floodwater during heavy rains.

“Just because you didn’t lose any homes in your town or neighborhood,” Fukutomi said, “doesn’t necessarily mean you’re totally out of danger ... if you live anyplace near the fire area.”

Times staff writer Greg Griggs contributed to this report.