On Wednesday, the state Department of Water Resources revealed a $1.1 billion cost estimate for the massive repair work at America’s tallest dam. The cost of the emergency response, and the subsequent repairs to the dam’s two flood-control spillways, has periodically risen since officials made their initial estimates following the crisis, which triggered the evacuation of 188,000 residents.
DWR spokeswoman Erin Mellon, citing the enormity of the repair project, told reporters on a conference call that cost estimates “may be adjusted further” as work continues into 2019. DWR said it expects to have the dam’s two spillways substantially rebuilt by Nov. 1 and ready for the winter rains.
The state expects the federal government to pick up the lion’s share of the costs.
The initial cost estimate was pegged at $200 million. In January, DWR officials said the price had grown to $870 million.
Mellon said the rising costs include more money to excavate the hillside beneath the dam’s emergency spillway, road construction and removal of debris and sediment from the Feather River channel at the base of the two spillways.
Since the crisis, state officials have said they expect the Federal Emergency Management Agency to reimburse the state for up to 75 percent of the costs, with the local water districts that store water behind Oroville Dam covering the rest.
So far Mellon said FEMA agreed to pay 75 percent of the $116 million in costs submitted by the state. That figure hasn’t changed since January. Mellon said the state is still submitting expenses to FEMA for possible reimbursement, but the process could take a long time before it’s all sorted out.
But the possibility that FEMA could reject some of the state’s funding requests has lingered since the spring 2017 when then-DWR Director Bill Croyle told a legislative hearing that FEMA could reject reimbursement if the agency believed the crisis was caused by poor maintenance.
In January, a team of independent engineers concluded that poor maintenance was a factor in the emergency, along with poor design and construction. The forensic team said the state and federal officials who inspected Oroville Dam relied too heavily on visual inspections, ignoring blueprints, construction records and other documented clues that could have warned them about the dam’s troubled flood-control spillway long before it fractured in February 2017.
The team said the spillway failure at Oroville was likely caused by longstanding problems with cracks in the concrete and a faulty drainage system underneath the concrete chute that was too thin in places.
Mellon said Wednesday that the forensic team’s conclusion isn’t expected to jeopardize reimbursement by FEMA. The team “clearly stated that the incident couldn’t have been prevented based on what was current practices on inspections and evaluations by dam owners and regulators, both state and federal,” she said.
Neither spillway has been activated since spring 2017. State officials said the main spillway could have been safely used if water levels had risen high enough at Lake Oroville.
Oroville’s crisis began Feb. 7, 2017, when a giant crater appeared in the dam’s main spillway as heavy rains soaked Northern California, prompting dam operators to reduce water releases in an effort to limit the damage.
As the reservoir filled, water poured over the never-used emergency spillway, which rests atop an unlined hillside that holds back the lake.
The hillside began eroding. Fearing it would collapse and unleash “a wall of water,” law enforcement ordered the immediate evacuation of 188,000 downstream residents. The crisis passed when dam operators dramatically ramped up water releases from the main spillway, lowering lake levels.
Residents were allowed to return home after two days, but the water releases destroyed much of what was left of the main spillway, necessitating the two-year repair effort led by contractor Kiewit Corp. of Omaha, Neb.
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