Sadly, due to a decades-long failure of public leadership to build Auburn Dam which would provide Sacramento the Gold Standard of 400/500-year level protection—see our report on Auburn Dam on our website—Sacramento remains vulnerable to massive floods, as reported in this story from the Sacramento Bee.
An excerpt from the Bee article.
Taxpayers have spent billions of dollars on dams, levees and bypasses to keep Sacramento and other Central Valley towns and cities from flooding, but experts say the infrastructure would prove no match for a megastorm like the one that pummeled Houston this week.
“It’s still going to flood some day,” said Jeffrey Mount, a watershed expert with the Public Policy Institute of California. “There’s still going to be that rare large event, which will overwhelm us. Houston is the reminder that you cannot engineer your way out of flooding.”
Flood control officials in Houston say Hurricane Harvey has caused at least a 500-year flood, meaning it beat the 0.2 percent odds of that much rain falling at one time. Nearly 52 inches dumped on Houston in four days, according to the National Weather Service. That’s the most ever recorded for a single storm in the continental U.S., and about what Sacramento usually receives over a three-year period.
Could such a megastorm happen here? It would be bigger by far than any ever recorded, but experts say climate change is making what were once considered impossible storms more likely.
And like Houston, whose infrastructure was rated for 100-year-flood protection (a 1 in 100 chance of flooding in a given year), a megastorm of that size would almost certainly overwhelm the Sacramento region’s flood-control defenses.
Much of the Central Valley still lacks 100-year-flood protection, and many of the rural areas have levees that are only rated for 50-year floods, said Joe Countryman, a retired U.S. Army Corps engineer who sits on the Central Valley Flood Protection Board.
After Hurricane Katrina, the Legislature in 2007 ordered California’s urban areas to be protected from a 200-year flood. Levee upgrades and other flood-protection improvements are underway to meet that goal in Sacramento, but they’re still years away from completion.
When finished, the upgrades should prove more than adequate to protect Sacramento from the largest floods ever recorded, but the region’s flood protection system still wouldn’t withstand a storm like Harvey, Countryman said.
“If it happens, there’s going to be devastation,” he said. “If we get a 500-year flood on the American River, there’s going to be huge amount of damage in Sacramento.”