More than 180,000 Californians have been evacuated from below the Oroville Dam, because officials fear the emergency spillway could fail, unleashing a deadly flow of water.
After a years-long drought, billions of gallons of rain and melted snow have flooded into the reservoir in the last few weeks, filling it to the brim.
More precipitation is expected in the coming days.
The problem developed when officials released tons of water – about 100,000 cubic feet per second – down the spillway to lower the water level and it started eroding, leaving a chasm gaping in the channel.
Officials switched the water that needs to be released to an emergency spillway, but it dropped the water onto the dirt hillside, and the erosion there began immediately. Officials were left with the no-win choice of sending the water down a broken main spillway or down an emergency path in which the erosion could threaten the stability of the top of the dam itself.
The evacuation was ordered when officials feared the damage would undermine the 1,730-foot-long concrete lip at the top of the emergency spillway and unleash billions of gallons of water in a short time.
It didn’t have to be that way.
The Friends of the River, the Sierra Club and the South Yuba Citizens League had told the government more than 10 years ago that in addition to the concrete main spillway, the emergency route down a hillside also needed to be covered with concrete.
Tony Francois, a senior attorney for the Pacific Legal Foundation, whose organization has fought multiple battles over property rights including water rights, told WND the issue with Oroville isn’t unique, as there are multiple fights over water rights and paying for their maintenance.
But he said the current problem is that the reservoir is at its highest level ever, and the release of water is causing damage.
In an editorial, the San Jose Mercury News pointed out state and federal officials “decided in 2005 to ignore warnings that the massive earthen spillway adjacent to the dam itself could erode during heavy winter rains – which it has done – and cause a calamity, which it very nearly did this week and could yet do by the end of winter.”
Environmentalists don’t routinely recommended that hillsides be covered with concrete, but in this case, the question had been raised as part of the reservoir’s relicensing procedure in 2005.
The environmental groups urged “federal officials to require that the dam’s emergency spillway be armored with concrete rather than remain as just a hillside.”
Said the paper: “We need a full investigation of the state’s re-licensing procedures for this and other critical dam infrastructure. It should include the role played in the Oroville evaluation by the association of 27 agencies that buy water from the state through the State Water Project – not only the Metropolitan Water District, which supplies water for Los Angeles and San Diego, but also the Santa Clara Valley Water District and the Alameda County Water District.
“If we get through this winter without loss of lives and many more billions of dollars in property loss expected from the failure of the Oroville spillway, then we can take this as a fortuitous warning to prevent other disasters. But that’s still a big ‘If.’ Storm clouds return Thursday.”
Francois said the decision back then was based on the costs and the benefits. And he pointed out that the current situation is unprecedented.
“This is not the crisis management even they expected to be in,” he said.
He said the current strategy is to shore up the failing spillway with bags of boulders dropped by helicopter.
Officials this week are urgently trying to lower the water level behind the 700-foot-tall dam by about 50 feet.
According to the London Daily Mail, Billy Croyle, the acting chief of the Department of Water Resources said he had ordered staff members to flee the area, because experts thought the dam would fail.
They joined nearly 200,000 others told to leave a 40-mile stretch of the Feather River below the dam.
The evacuations were ordered on Sunday along a 40-mile stretch of the Feather River below the dam after authorities said its emergency spillway could give way.
It appeared no one expected a full collapse of the dam, but officials did say a 30 foot “tsunami” could be unleashed.
Butte County Sheriff Kory Honea said in the Mail report that residents would be allowed to return when it’s safe – but he “offered no timetable for when” that would happen.
The report continued, “Meteorologists are predicting the rain to begin on Wednesday night, dumping up to four inches by Thursday morning with more to drain from the mountains during the day.”
On Monday, loads of rock were being dropped by helicopters onto the crumbling spillway.
Oroville is America’s tallest dam and experts predicted that if it failed, water could reach Oroville within an hour, and within eight to 12 hours it would be in Yuba City. They say the flood could be 10 feet deep at that point.
The damage to the emergency spillway had been predicted by experts.
The News reported John Onderdonk, a civil engineer in the Federal Energy Regulatory Commission’s San Francisco office, in 2006 told his bosses: “The emergency spillway meets FERC’s engineering guidelines for an emergency spillway. The guidelines specify that during a rare flood event, it is acceptable for the emergency spillway to sustain significant damage.”
Ron Stork of the Friends of the River told the News, “I’m feeling bad that we were unable to persuade DWR and FERC and the Army Corps to have a safer dam.”