OROVILLE: Butte County A foaming mass of
whitewater cascaded down the badly damaged Oroville Dam spillway Friday after
state officials upped the flow in an attempt to avoid what would be an even
more disastrous overflowing of California’s second-largest reservoir.
By increasing the flow, dam operators were
conceding they were likely to lose a big portion of the spillway to erosion perhaps
the entire bottom half, or about 150 yards of concrete that will have to be
painstakingly rebuilt during the dry months. The cost, state officials said
Friday, will likely top $100 million.
As they spoke, the gaping hole in the
spillway which first cracked open Tuesday got bigger as 65,000 cubic feet of
water per second ripped into it, causing a rain-like mist to fall throughout
the area just as the real rains that had caused the debacle ceased.
“We’re going to lose a lot of the spillway,”
said Chris Orrock, a spokesman for the California Department of Water
Resources, which manages the nation’s tallest dam, about 75 miles north of
Sacramento. “The director has said we are willing to lose the bottom of that
spillway to make sure we maintain flood control for the downstream
communities.”
The torrent was crashing over the side of the
spillway onto a bed of rocks, scouring the hillside clear of vegetation and taking
with it so much dirt that the Feather River turned into a soup full of debris,
endangering millions of hatchery fish downstream. As of Friday afternoon,
Orrock said, more water was still flowing into the reservoir which can hold 3.5
million acre-feet of water and helps supply farms and million of people than
was coming out.
If the water rose about 10 more feet, he
said, it would begin gushing over the dam’s emergency spillway, a dirt channel
21 feet below the brim that has never been used in the structure’s 48-year
existence. That spillway has been criticized as deficient and dangerous by
environmental groups. A 2002 analysis by the Yuba County Water Agency said use
of the auxiliary spillway would cause “severe erosion” and deposit so much
debris in the river that downstream structures could be damaged.
Although officials didn’t expect to have to
use the emergency spillway, forestry workers were clearing trees and other
debris from the channel just in case.The good news, Orrock said, is that the larger
spillway, made of reinforced concrete, was peeling downward and not threatening
the integrity of the 770-foot-high dam itself. “If the erosion was moving up
toward the dam, they would stop the flow,” he said.
Nearby Oroville residents were still worried.
Dan Rogers and several of his friends were so afraid of flooding Thursday that
they left town and spent the night miles away in Chico. “It’s pretty crazy,”
said Rogers, who returned after the rain stopped.
Although officials said the area wouldn’t flood,
the frothing Feather River had picked up so much muck that it was threatening
to asphyxiate millions of salmon 4½ miles downstream at the Feather River Fish
Hatchery, forcing workers to frantically collect 8 million hatchlings and truck
them 10 miles to a holding pond that uses well water.
The water flowing into the hatchery was
measured to be 20 times as muddy as normal, said Harry Morse, a spokesman for
the state Department of Fish and Game. He said 6 million fish had been moved
and that hatchery staffers would work through the day and night moving 2
million more. As many as 2 million of the 2-inch-long juvenile fish, though,
will have no place to go.
“You can only put so many fish in one place
without them lacking oxygen,” he said. “We hope to get the silt settled. If we
can’t do that, we may have to let the last 2 million loose in the Feather River
floodplain.”The Feather River hatchery produces more than half of all the
salmon caught in the ocean and rivers, the most of any hatchery in California,
which boasts a multimillion-dollar salmon industry.
“We’re in an emergency situation,” Morse
said. “This is stuff that has never happened in the 48 years of the dam, so we
are really scrambling. We’re bringing staff, engineers, trucks in. It’s a
full-court press.” The forecast called for a five-day window of clear weather,
and engineers plan to use the time to assess the situation and figure out what
fixes need to be made. Clearly, though, the destruction is extensive.
Kevin Dossey, a civil engineer for the
Department of Water Resources office in Oroville, said repairs to the spillway
would likely take four to five months and cost more than $100 million. On the
hook for payment, state officials said, are beneficiaries of the California
State Water Project 29 urban and agricultural water agencies that include the
mammoth Metropolitan Water District of Southern California and the Santa Clara
Valley Water District.
“It wouldn’t be surprising that state water
contractors would be paying the bill,” said Jim Fiedler, the chief operating
officer for the Santa Clara Valley Water District. “But we would certainly hope
that they would seek emergency funding to help pay for it.”
While the cause of the break in the spillway
is not yet known, officials said repairs were made on the chute in 2013 after
it was used during storms in 2011 and 2012. Dossey said he wasn’t sure whether
the fixes were made in the same area as the new damage. “I don’t think anybody
on the inspection team or repair team would say more should be done because
there wasn’t any evidence more needed to be done,” Dossey said. “The repairs
were smooth.”
An inspection of the dam and spillway in July
2015 deemed it safe, but experts did not walk the sloped surface to look for
cracks and other potential problems, state records show. A “visual inspection
from some distance indicated no visible signs of concrete deficiencies,” said
the report compiled by the Division of Safety of Dams, a branch of the
Department of Water Resources.
It wasn’t clear why inspectors didn’t walk
the spillway’s discharge chute, and a spokesperson for the agency didn’t
respond to a request for comment. The dam also passed an inspection earlier in
2015.
Dam operators first noticed an eroded section
of the spillway Tuesday as they attempted to increase the flow down the chute
during a rainstorm. They shut it down to take stock of the damage, but as the
rain increased, they had no choice but to increase flows, causing the fissure
to balloon outward.
The dam’s spillway and valves in the Edward
Hyatt Power Plant at the bottom of the reservoir were releasing 79,000 cubic
feet per second of water Friday, but the flow was reduced overnight. About
130,000 cubic feet per second was flowing into the dam from the surrounding
mountains. If it were not damaged, the spillway could usher out up to 200,000
cubic feet per second of water, though that flow would be too much for the
Feather River, which can handle 150,000 cubic feet per second without flooding.
Oroville Dam operators previously came under
scrutiny in 2009 after a wall collapsed at the Hyatt Power Plant and five
employees were nearly sucked out of the building by a powerful vacuum, causing
one man to suffer broken bones and other serious injuries and spend four days
in a hospital.
State workplace safety regulators found the
Department of Water Resources was at fault for ordering the workers to open
valves that were missing a critical part and couldn’t handle the pressure.
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