SAN FRANCISCO, Sept. 12 (UPI) -- Several U.S. cities that depend on levees for protection need to learn from New Orleans where the levees were breached by Hurricane Katrina.
A prime potential trouble spot is in Northern California, where hundreds of thousands of people live on low-lying areas protected by levees, USA Today reported.
Similar levee networks also protect the Gulf Coast, in Florida and in heavily populated areas of the Midwest along the Mississippi and Missouri rivers, the report said.
"Levees are ubiquitous," says Gerry Galloway, a civil engineer who led a blue-ribbon study aimed at updating U.S. flood management after the devastating flooding along the upper Mississippi in 1993. "There are levees that are marginal and levees that we don't know the answer to whether or not they're marginal. That's the worrisome part."
Experts say an earthquake or prolonged, heavy storms could cause levees to rupture near California's urban areas, particularly around Sacramento.
Major levees built and inspected by the U.S. Army Corps of Engineers are more reliable than locally built levees. But even they can hide dangers, the report said.
