So with more signs of a strong El Niño winter, what can people do to prepare for the possibility of heavy rain?
That's the question many people are asking in the wake of a new forecast this week. The National Weather Service's Climate Prediction Center said Thursday that this El Niño is shaping up to be as strong as the 1997-98 El Niño, which sent storms that killed 17 people and caused more than $550 million in damage in California.
How are local officials preparing for El Niño?
Many agencies are doing their own El Niño planning. Supervisors Michael D. Antonovich and Hilda Solis will ask for a full investigation into the county's preparedness at all county flood-control facilities.
Los Angeles County Flood Control District officials said they have cleared debris basins and flood-control channels throughout the county — the first line of defense against mudslides — and made some improvements to dams and other infrastructure since the county's last major rainstorms in 2004-05.
Is there a specific area of concern?
At Devil's Gate Dam in Pasadena, debris that accumulated as a result of the Station fire has put neighborhoods downstream along the Arroyo Seco in danger of flooding.
Los Angeles County plans to remove 2.4 million cubic yards from the Hahamongna flood-control basin above Devil's Gate Dam over the next five years. Some neighbors, outdoor recreation enthusiasts and environmentalists who oppose the project are suing to stop it.
But the sediment removal project will not start until next year. The county has not yet awarded a contract for the work, said Keith Lilley, who oversees a group of county Department of Public Works staff who respond to storm events.
There is risk of flooding south of the dam — affecting the 110 Freeway, Pasadena, South Pasadena and northeast Los Angeles — if the San Gabriel Mountains are soaked with a series of unrelenting storms and send large amounts of mud, rocks and burned trees into a full basin, officials said.
“If we had multiple major storms with sediment, the reservoirs would fill up and we would have very little capacity for flood control and water capture,” Lilley said.
A 2011 county report painted a grim picture of what would occur if huge rainstorms hit Devil's Gate. Under a worst-case scenario, torrential rains could send mud, rocks and water over the dam and flooding into the Rose Bowl, South Pasadena and northeast Los Angeles in less than 40 minutes.
A subsequent report said the Rose Bowl probably wouldn't be flooded in a single storm but could be at greater risk after a series of storms if sediment isn't quickly removed from areas downstream from the dam.
Are there some basic tips about how to prepare for possible flooding?
Yes. Here is an illustrated guide from Santa Barbara County.
And here are some key points from the city of Los Angeles:
Here are some tips from the Federal Emergency Management Agency
Before the rains:
During the rains:
After the rains:
How bad was the 1997-98 El Niño?
It started in October 1997 in Mexico, when a hurricane fueled by El Niño slammed into Acapulco, causing massive flooding and hundreds of deaths.
A few weeks later, storms started hitting Southern California. Then in December, the skies opened up in Orange County in what meteorologists described as the biggest rainstorm in a century. More than seven inches fell in parts of south Orange County in one day. Mobile-home parks in Huntington Beach flooded, forcing rescuers to use inflatable boats and a catamaran to rescue residents. Mudslides destroyed hillside homes. Neighborhoods flooded. Major roads were made impassable by debris.
And that was just the beginning. Over the next few months, a series of powerful storms caused havoc, washing away roads and railroad tracks, overflowing flood control channels, causing 17 deaths and more than half a billion dollars in damage in California. The toll was far worse in Mexico, where Tijuana and other cities faced crippling flooding.
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