2/12/17, "Oroville Dam: Feds and state officials ignored warnings 12 years ago," Mercury News, Paul Rogers
"More than a decade ago, federal and state officials and some of
California’s largest water agencies rejected concerns that the massive
earthen spillway at Oroville Dam— at risk of collapse Sunday night and prompting the evacuation of 185,000 people — could erode during heavy winter rains and cause a catastrophe.
Three environmental groups — the Friends of the River, the Sierra Club
and the South Yuba Citizens League — filed a motion with the federal
government on Oct. 17, 2005, as part of Oroville Dam’s relicensing
process, urging federal officials to require that the dam’s emergency spillway be armored with concrete, rather than remain as an earthen hillside.
The groups filed the motion with FERC, the Federal Energy Regulatory
Commission. They said that the dam, built and owned by the state of
California, and finished in 1968, did not meet modern safety standards
because in the event of extreme rain and flooding, fast-rising water
would overwhelm the main concrete spillway, then flow down the emergency
spillway, and that could cause heavy erosion that would create flooding
for communities downstream, but also could cause a failure, known as
“loss of crest control.”...
FERC rejected that request, however, after the state Department of
Water Resources, and the water agencies that would likely have had to
pay the bill for the upgrades, said they were unnecessary.
agencies included the Metropolitan Water District of Southern
California, which provides water to 19 million people in Los Angeles,
San Diego and other areas, along with the State Water Contractors, an
association of 27 agencies that buy water from the state of California
through the State Water Project. The association includes the
Metropolitan Water District, Kern County Water Agency, the Santa Clara
Valley Water District and the Alameda County Water District.
Federal officials at the time said that the emergency spillway was
designed to handle 350,000 cubic feet per second and the concerns were
“It is important to recognize that during a rare event with the
emergency spillway flowing at its design capacity, spillway operations
would not affect reservoir control or endanger the dam,” wrote John
Onderdonk, a senior civil engineer with FERC, in the Federal Energy
Regulatory Commission’s San Francisco Office, in a July 27, 2006, memo
to his managers.
“The emergency spillway meets FERC’s engineering guidelines for an
emergency spillway,” he added. “The guidelines specify that during a
rare flood event, it is acceptable for the emergency spillway to sustain
This weekend, as Lake Oroville’s level rose to the top and water
couldn’t be drained fast enough down the main concrete spillway because
it had partially collapsed on Tuesday, millions of gallons of water
began flowing over the dam’s emergency spillway for the first time in
its 50-year history.
On Sunday, with flows of only 6,000 to 12,000 cubic feet per second —
water only a foot or two deep and less than 5 percent of the rate that
FERC said was safe — erosion at the emergency spillway became so severe
that officials from the State Department of Water Resources ordered the
evacuation of more than 185,000 people. The fear was that the erosion
could undercut the 1,730-foot-long concrete lip along the top of the
emergency spillway, allowing billions of gallons of water to pour down
the hillside toward Oroville and other towns downstream.
Such an uncontrolled release from California’s second-largest
reservoir while it was completely full could become one of the worst dam
disasters in U.S. history....
Lester Snow, who was the state Department of Water Resources director
from 2004 to 2010, said Sunday night that he does not recall the
specifics of the debate during the relicensing process 11 years ago.
“The dam and the outlet structures have always done well in tests and
inspections,” Snow said. “I don’t recall the FERC process.”...
A filing on May 26, 2006, by Thomas Berliner, an attorney for the
State Water Contractors, and Douglas Adamson, an attorney for the
Metropolitan Water District of Southern California, discounted the risk.
It urged FERC to reject the request to require that the emergency
spillway be armored, a job that would have cost tens, if not hundreds,
of millions of dollars.
“The emergency spillway was designed to safely convey the Probable
Maximum Flood, and DWR has reviewed and confirmed the efficacy of the
PMF hydrologic analysis for Oroville Reservoir,” the attorneys noted.
Ultimately, they were successful. FERC did not require the state to upgrade the emergency spillway."