FRESNO, Calif. (AP) More than half of California’s levees do not meet flood-control standards and need up to $17 billion in repairs and investment, officials said in the first statewide flood plan released Dec. 30.
The plan, issued by the Department of Water Resources, details the dire status of levees and other infrastructure along the Sacramento and San Joaquin river systems.
Officials and experts say the state’s flood control system — a piece-meal collection of 14,000 levees and other infrastructure built by farmers and local governments over the last 150 years — is no longer adequate. The Central Valley, once a mostly agricultural area that was lightly populated, has experienced rapid development and population growth.
“The system is based on antiquated technologies, so you have to upgrade it and keep in mind changing societal demands,” said Jeffrey Mount, professor and founding director of Center for Watershed Sciences at UC Davis. “Modern flood control is wickedly complicated, because it has to take into account a lot of factors.”
Experts say the aging levees, if breached, pose a great threat to life, property and the state’s drinking water supplies. Central Valley’s flood risk ranks among the highest in the nation.
While officials have long known the system was neglected and in disrepair, it’s the first time they have studied it as a whole, come up with long-term solutions and a priority for investments.
More than half of 300 mi. of aged urban levees do not meet modern design criteria, according to newly released analysis. And about 60 percent of 1,230 mi. of non-urban levees have a high potential for failure from under-seepage, through-seepage, structural instability, and/or erosion.
In addition, about half of the 1,016 mi. of channels are believed to be inadequate to handle projected flooding. And two bridges are in need of repairs.
About 1 million Californians now live in floodplains, and levees protect an estimated $69 billion in assets, including the state’s water supply system, major freeways, agricultural land and the valley’s remaining wetland and riparian habitat, said Mike Mierzwa, senior engineer in the Central Valley Flood Protection Office.
“The challenge that we have is that the flood management system in the valley is dated and is not functioning in ways it was designed,” Mierzwa said. “We have people living behind levees which were meant to protect farmland.”
In 2006, in the wake of Hurricane Katrina, former Gov. Arnold Schwarzenegger declared a state of emergency for California’s levee system and ordered emergency levee repairs to the 33 most critical spots at a cost of $175 million. That same year, state voters approved nearly $5 billion in bond funds for flood protection projects statewide.
Legislators also mandated that the state develop a plan to reduce flood risks and guide the investments of the bond money.
The plan calls for $14 billion to $17 billion in repairs and other investments — including the $5 billion in bond funds already approved. Investments would be spread over the next 20 to 25 years.
Officials said the money would come from a mixture of federal, state and local sources. They said voters will need to approve more bonds.
Most of the money — up to $6 billion — would be spent in urban areas, where risk is greatest and thousands of homeowners and their property could be affected in case of a flood. Another $6 billion would go towards system-wide improvements.
The plan doesn’t call for specific projects, but offers recommendations. Those include extensive bypass expansion and the construction of a new bypass; major improvements to intake, weir and gate structures; sediment removal projects; urban and rural levee repairs; fish passage improvements and ecosystem restoration.
The plan doesn’t recommend building new reservoir storage, which is very expensive.
Focusing on other projects beyond levee repairs is a good step forward, Mount said.
“There’s always the pressure to simply fix the problem, meaning just make the levies taller and stronger. That’s the path of least resistance,” he said. By constructing and strengthening levees, Mount said, the state may actually induce development and growth behind the levees and hence increase flood risk. Thus the need, he said, to prioritize investments to areas where risk reduction is greatest.
Thus far, state officials say they have spent about half of the $5 billion in bond funds on more than 200 projects. Those include flood emergency exercises, 120 critical levee erosion site repairs, the removal of three million cubic yards of sediment from the bypasses and substantial levee improvement projects, among others.
The Central Valley Flood Protection Board must adapt the plan by July 2012.