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Flood risk high for West Sacramento | Business

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Flood risk high for West Sacramento
Flood risk high for West Sacramento

"West Sacramento will be inundated" in a 200 year flood event, said California Department of Water Resources Assistant Flood Management Division Chief Paul Marshall in a June 20 presentation to the West Sac City Council.

Marshall characterized as 'conservative' DWR's new 200 year flood inundation maps that outline risks to communities in the Central Valley. (A 200 year flood, with consequences like the flooding that decimated New Orleans, has a half percent chance of happening in any year, say flood experts like West Sac's former Flood Protection Manager Michael Bessette.) Marshall said DWR worked with the Army Corps of Engineers hydrologists to create the maps.

Last year, Marshall said, the California Legislature ordered DWR to do the maps after Senator Lois Wolk (D-Davis, whose district then-included West Sacramento) and area flood protection agencies said they needed  them. California requires that levees be able to withstand a 200 year flood. Marshall said the legislature wants to "get going" on "enforcement."

DWR tried to produce inundation maps that weren't "too outlandish" (create panic), Marshall said. Even so, Councilman Bill Kristoff told him the West Sac inundation presentation "scared the hell out of us."

West Sac levees fall short of the flood protection of levees in upstream communities such as Natomas, Marshall told the council. Built taller and stronger, Natomas levees "are holding," he said, and could survive a potentially catastrophic flood. "West Sacramento," he said, "wasn't given that."

He warned that levees 'holding' upstream increase the volume of water rushing toward West Sac when the Sacramento River is high. In a 200 year flood, Marshall said, DWR's new map "shows the basin of West Sacramento as inundated" if its levee fails or is over-topped by flood water.

West Sac is surrounded by water held back by its 52 miles of levee, Mayor Christopher Cabaldon has said in a previous council meeting. He's warned that such flooding would be 'horrific' in lost lives, lost property, lost pets, "everything we care about."

Marshall credited West Sac for being 'ahead of the curve,' with three levee fixes done and a fourth on tap. The Corps' GRR (General Re-evaluation Report) for West Sac's levees is due by December or January of next year, he said. The report is the first step in securing more federal funding for levee fixes, West Sac's flood protection experts say. They, acknowledge that much of the city's levee system would not meet the 200 year flood protection standard.

Legislation recently co-sponsored and introduced by Representative Doris Matsui (D-CA) could, if enacted, break the log jam in DC that has held up federal levee "credits" for cities like West Sac. (Matsui's Congressional district now includes West Sacramento.) Army Corps credits for completed levee work reduce how much small communities pay as their share of cost for future levee projects.

Mayor Christopher Cabaldon thanked Marshall for his 'frank presentation,' and said "the incredibly conservative (maps)" should be "a wake up call" for West Sac residents who should buy flood insurance now.

DWR's maps, when released, will include how deep the flood water will be if West Sac experiences a 200 year flood-inundation. A West Sacramento Area Flood Agency 2007 report foresees water as deep as 10 feet in some areas. The completed inundation map will have present day projections.

Marshall said this is the first time the state has done informational 200 year flood inundation maps for the Central Valley.

For West Sac, he said, "It doesn't look pretty."

Contact Carol Bogart at 3bogart@gmail.com.