Fight to Prevent Oroville Dam Overflow Nightmare Reaches Frantic Level in California; Thousands of Homes Abandoned as Officials Brace for the Worst

More than 100,000 people were told to evacuate from areas near Oroville Dam in Northern California on Sunday because officials feared that an emergency spillway could fail, sending huge amounts of water into the Feather River, which runs through downtown Oroville, and other waterways.

With more storms expected to slam Northern California later this week, officials worked frantically Monday to drain water from brimming Lake Oroville in hopes of heading off a potentially catastrophic flood.

  • The mass evacuations cap a week of frantic efforts to prevent flooding as the reservoir behind the United States’ tallest dam reached capacity and its main spillway was severely damaged.
  • The damage occurred even though the spillway was designed to handle much more water than the amount that overflowed. Some questioned why officials didn’t heed suggestions more than a decade ago to fortify the emergency spillway.
  • If the head of the spillway crumbles, a 30-foot wall of water could go crashing down the hillside into the Feather River and toward Oroville, Marysville and Yuba City.

Scrutiny continued to grow over the emergency spillway at Oroville Dam after it eroded Sunday, forcing the evacuations of more than 100,000 people.

The damage occurred even though the spillway was designed to handle much more water than the amount that overflowed. Some questioned why officials didn’t heed suggestions more than a decade ago to fortify the emergency spillway.

Earth and weak rock near the top of the spillway started to erode when peak flows were 12,600 cubic feet per second, compared with the designed capacity of 450,000 cubic feet per second, according to the Department of Water Resources. The erosion happened so quickly that officials feared the concrete wall would be undermined, and ordered sweeping evacuations in Butte, Yuba and Sutter counties that remained in effect Monday night.

With more storms expected to slam Northern California later this week, officials worked frantically Monday to drain water from brimming Lake Oroville in hopes of heading off a potentially catastrophic flood.

Bill Croyle, the acting director of the Department of Water  Resources, said Monday that he was “not sure anything went wrong. This was a new, never-happened-before event.”

But during 2005 relicensing proceedings for Oroville Dam, several environmental groups argued that substantial erosion would occur on the hillside in the event of a significant emergency spill. In a filing, they asked the Federal Energy Regulatory Commission to order the state to “to armor or otherwise reconstruct the ungated spillway.”

State Water Project contractors, including the Metropolitan Water District of Southern California, were involved in the relicensing. MWD General Manager Jeffrey Kightlinger said Monday his agency deferred to the state and federal agencies on the matter.

“They did look at that issue and they determined that [the existing emergency spillway] did meet the appropriate FERC guidelines,” Kightlinger said. “In the FERC guidelines, they talk about how you don’t put a lot of funding and concrete, etc. into emergency spillways because presumably they will rarely if ever be used.”

“We did not say it was a cost issue,” he added.

Brown, after meeting with advisors at the state’s emergency operations center near Sacramento, was asked by reporters about the concerns raised in 2005 about Oroville’s spillway system.

He said he welcomed calls for more scrutiny. “We’re in a very complex society where things can go wrong,” he said. “When they do, they ripple out and affect hundreds of thousands and in some cases millions of people.”

Click here to continue reading…

SOURCE: The Los Angeles Times