California dam evacuees can return home, but need to be ready to leave again
Authorities say the risk of the dam collapsing has been significantly reduced
Authorities lifted an evacuation order Tuesday allowing 200,000 California residents who live below the nation's tallest dam to return home after declaring the risk of a catastrophic collapse of a damaged spillway had been significantly reduced.
Butte County Sheriff Kory Honea said residents can return home immediately. State water officials said they have drained enough of the lake behind Oroville Dam so that its earthen emergency spillway will not be needed to handle runoff from an approaching storm.
Residents returning home "have to be vigilant," and "there is the prospect that we will issue another evacuation order ... if the situation changes," the sheriff said.
Officials had ordered residents of the region, 242 kilometres northeast of San Francisco, to flee to higher ground Sunday after fearing a never-before-used emergency spillway was close to failing and sending a 10-metre wall of water into communities downstream.
Rod Remocal of Biggs, west of Oroville, said the announcement "took a big load off" of him. He called it "the thrill of relief."
The decision to lift the order came abruptly, just as the evacuation order Sunday night came shortly after officials said there was no threat.
The sheriff said water was being released through the dam's damaged primary spillway without further harm to the concrete structure. Work to cover the earthen emergency spillway with rocks and cement was on pace to beat the next rain, and those storms would be less potent.
"As a result of these actions, the risks that we faced when we initiated those evacuations have significantly been reduced," Honea said.
"This reduction to an evacuation warning properly balances the need for people to resume their daily lives while at the same time being prepared to deal with future increased threat," he added.
The decision came as helicopters carried giant sandbags and cement blocks from a staging area on the south side of Oroville Dam toward the stricken spillway on the north side. Crews operating heavy equipment loaded rocks and boulders into dump trucks, which carried them over the dam and dumped them on damaged portions.
Bill Croyle, acting director of the state Department of Water Resources, said that as of noon Tuesday, water was flowing into the lake at a rate far lower than the water being released.
"That means we're continuing to make significant gains," Croyle said.
The surface of the reservoir was nearly four metres lower than at its peak height, and the water release, described as the greatest in the dam's nearly half century, will continue to lower the surface a total of 15 metres.
The National Weather Service's Sacramento office said the incoming rain would move through late Wednesday and Thursday morning, with five centimetres to 10 centimetres expected in the foothills and mountains. But the storm was looking colder than initially projected, meaning less snow and less run-off than last week's storms.
White House spokesman Sean Spicer told reporters Tuesday the administration would "make sure we are doing everything we can to attend to this matter" and "help people who have been impacted," adding that the dam was evidence that the United States needed to overhaul its infrastructure, one of Trump's domestic goals.
On Tuesday evening, the government announced that three counties in the area will receive federal disaster assistance.
The earth-filled dam is just upstream and east of Oroville, a town of about 16,000 people. At 230 metres high, the structure, built between 1962 and 1968, is some 12 metres taller than the Hoover Dam.
On Monday afternoon, crews dropped large bags filled with rocks into a gap at the top of the emergency spillway to rebuild the eroded hillside.
The main spillway, a separate channel, is also damaged because part of its concrete lining fell apart last week. Both spillways are to the side of the dam itself, which has not been compromised, engineers said.
A consequence of the <a href="https://twitter.com/hashtag/OrovilleDam?src=hash">#OrovilleDam</a> evacuation, nearby town overrun by released or escaped chickens <a href="https://t.co/DRoN9VwAGL">pic.twitter.com/DRoN9VwAGL</a>—@kimbrunhuber