“A Never-Happened-Before Event”: As Oroville Dam Drains, A Problem Remains


As discussed previously, the biggest priority for California officials tasked with restoring the damaged Oroville Dam as they race against a coming Wednesday storm, is to plug the hole in the damaged spillway while draining as much water as possible ahead of the coming rainfall.

The good news, as the chart below shows, is how the water level at the Oroville reservoir has been declining over the last 24 hours. According to a spokesman for the Department of Water Resources water is pouring down the facility’s damaged main spillway at a rate of about 100,000 cubic feet per second, or more than twice the rate as water flowing into it. By 10 a.m., the lake’s water level was 4 feet lower than the emergency spillway, which suffered damage during its first ever water release over the weekend. Officials added that the water level of Lake Oroville has been steadily dropping at a rate of roughly 3 to 4 inches per hour.

A subsequent tweet by the California Office of Emergency Services updated that as of 12:30pm Pacific, the lake level had declined to 6 feet below the damaged emergency spillway.

Video from 12:30 today. Water released over Lake Oroville spillway at 100K cfs. Lake level 6′ below Emerg. spillway.

Workers with the CA Department of Water Resources are scrambling to reduce the lake’s overall water level to 50 feet below the emergency spillway elevation of 901 feet. That mission has taken on added urgency ahead of the previously reported heavy rains expected later in the week. According to a subsequent tweet by the California DWR, the dam is now releasing over 110,000 cubic feet per second from the main Oroville Spillway, with the lake level dropping around 8′ per day.

The current flows from the dam can be seen in the tweet below:

Asked about the outflow, authorities admitted their confusion: “It’s hard to look at a crystal ball and predict how it’s going to evolve,” said Kevin Lawson of Cal Fire. The flow into the lake is roughly 37,000 cubic feet per second, so they’re shedding a net 60,000 or so cubic feet per second.  They’re hoping to drop 8 feet per day.

It’s unclear if they’ll hit the target of lowering the lake by 50 feet before the next rain hits. But they’re expecting a smaller level of precipitation at a cooler temperature, so it may not run into the lake as quickly, giving them more time.

“We’re going to deal with that as it comes in,” said acting state Department of Water Resources Director Bill Croyle.

There were also questions about problems with the emergency spillway, which began eroding instead of serving its function.

“I’m not sure anything went wrong,” Croyle said. “This was a new, never-happened-before event.”

* * *

Earlier in the day, California authorities released various photos showing the situation at the Oroville Dam as of noon Pacific time. As noted, water levels at the reservoir have receded, and the damaged emergency spillway is no longer receiving water. But the damaged main spillway is still going strong, as the photos below show. The photos also show the erosion along the emergency spillway.

View image on TwitterView image on TwitterView image on Twitter

Current images of the from @CHP_Valley Air Operations’ H24, which is providing law enforcement support. @Cal_OES @CaltransHQ

Oroville Dam current outflow 100K cfs, water level dropping +4ft since releases increased yesterday. Update planned for 12pm @kcranews

While the lack of deterioration is good news, the LA Times has released the following map showing the areas which are still at risk of flooding near Lake Oroville.

And in addition to the threat of the upcoming rains, a residual risk with the emergency spillway is that the erosion from the overflowing water may erode the earth by the dam, destabilizing the structure. According to AP, the erosion at the head of the emergency spillway threatens to undermine the concrete wall and allow large, uncontrolled releases of water from Lake Oroville. Those flows could overwhelm the Feather River and other downstream waterways and levees and flood towns in three counties.

Department engineer and spokesman Kevin Dossey told the Sacramento Bee the emergency spillway was rated to handle 250,000 cubic feet per second, but it began to show weakness Sunday after flows peaked at 12,600 cubic feet per second.

The aerial photo above of the emergency spillway at Lake Oroville shows signs of major damage.

Meanwhile, perhaps because the worst possible outcome has failed to materialize, local officials have been forced to defend the order to evacuate nearly 200,000 people in the affected areas. The Butte County Sheriff Kory Honea on Monday defended his decision a day earlier calling for evacuations of more than 100,000 residents down river from the Oroville Dam after concerns that a spillway could fail and unleash a 30-foot tall wall of water on the region.

“I recognize and absolutely appreciate the frustration people who were evacuated must feel,” Honea said at a press conference. “It wasn’t a decision I made lightly.”

The calls for cities and towns downriver from Lake Oroville to evacuate were unexpected and triggered panic Sunday evening. Some people abandoned their cars on the highway and left with the clothes on their back after the Department of Water Resources announced that an emergency spillway would fail within the hour.

Honea shot down rumors the evacuation could end Monday afternoon. They’re working on a “repopulation” plan but there’s no timeline. “Getting those people home is important to me. But I have to be able to sleep at night knowing they’re back in that area,” he said.  His department had to move 500 inmates from Butte to Alameda County jail during the evacuation. They’re being held there for the time being.

This means that the over 188,000 residents of Yuba, Sutter and Butte counties who were ordered to leave their homes, are now in limbo and may not be able to return until the barrier at the nation’s tallest dam is repaired, according to Sheriff Honea. He did not say how long the fixes could take and offered no timetable for lifting the evacuation order. It also remains unclear what the current status of the plan to drop loads of rock on the eroded spillway at Oroville using helicopters.

Meanwhile, recalling the evacuation, local resident Nancy Borsdorf described a scene of chaos on her way out, including drivers abandoning cars as they ran out of gas. “People were just panicking,” said Borsdorf, who was at a shelter Monday in Chico.

“We’ve always loved and trusted our dam,” she said, having lived in Oroville for 13 years. “I’m really hopeful Oroville wasn’t flooded.”

Asked if the spillway was supposed to handle far more water, the acting head of California’s water agency said he was “not sure anything went wrong” on the damaged spillway according to AP. Bill Croyle said sometimes low-flow water can be high energy and cause more damage than expected. His comments came after officials assured residents for days that the damage was nothing to be concerned, then ordered everyone to get out in an hour.

The water level in the lake rose significantly in recent weeks after storms dumped rain and snow across California, particularly in northern parts of the state. The high water forced the use of the dam’s emergency spillway, or overflow, for the first time in the dam’s nearly 50-year history on Saturday.

The sudden evacuation panicked residents, who scrambled to get their belongings into cars and then grew angry as they sat in bumper-to-bumper traffic hours after the order was given. Raj Gill, managing a Shell station where anxious motorists got gas and snacks, said his boss told him to close the station and flee himself. But he stayed open to feed a steady line of customers.

“You can’t even move,” he said. “I’m trying to get out of here too. I’m worried about the flooding. I’ve seen the pictures — that’s a lot of water.”

“It was so scary. It was like a bad movie, everyone was panicking and driving crazy. It was really scary,” said Maribel Cervantes, 35, of Yuba City. Cervantes threw some clothes in a hamper and joined throngs of evacuees fleeing Yuba City late Saturday. She said she’s worried about getting back to work as a nursing assistant, but she still has deep concerns about potential flooding.

“How can they assure us that it’s safe?” she asked. “How can we be 100 percent sure when one minute they’re saying the spillway was about to collapse?”

Raul Nava, 29, waited until about midnight to leave his home in Yuba City. “We’re scared about flooding, our house is right next to the levees,” he said. “We just packed food, water, you know the basics, and headed out.”

Nava said he and his wife and his dad first tried to get in to an evacuation center in Colusa but were turned away. It took them five hours to reach the shelter in Woodland, he said. With him he brought his two pit bulls, and 10 pit bull puppies. “We’re ready to go home,” he said.

Merida Lozano, 40, of also of Yuba City, said she too left in a hurry Saturday afternoon. She and her four kids got to the emergency shelter at the Yolo County Fairgrounds around 1 a.m. after being turned away from several area hotels that were full, she said. “We had no clue what was going on until about 4, when we heard about the evacuation orders,” Lozano said. “The roads were empty and all of the sudden there were cars everywhere. My emotions are all over the place…at least we made it here with the kids.” Lozano said her sister stayed behind in Yuba City.

“We’re just waiting to go home right now,” she said. “I hope they learn from this and reinforce the spillway so that we aren’t in this position if this were to ever happen again.”

A Red Cross spokeswoman said more than 500 people showed up at an evacuation center in Chico, California. The shelter ran out of blankets and cots, and a tractor-trailer with 1,000 more cots was stuck in the gridlock of traffic fleeing the potential flooding Sunday night, Red Cross shelter manager Pam Deditch said. A California Highway Patrol spokesman said two planes would fly Monday to help with traffic control and possible search-and-rescue missions.

Other shelters have been reporting they are now full.

The Paradise Alliance Church is not longer accepting new evacuees. If seeking shelter visit http://www.buttecounty.net  for updated list.

While some shelter sites were at capacity, people were still trickling in to the Yolo County Fairgrounds Monday morning. The parking lot was about half full, and deliveries of cots and water were still coming in. Yolo County health officials, law enforcement and mental health experts were on site to assist.

To manage the chaotic exodus and ensure evacuated towns do not become targets for looting or other criminal activity, at least 250 California law enforcement officers were posted near the dam and along evacuation routes.

This afternoon Oroville vice mayor Janet Goodson, who is marooned in Red Bluff after evacuating Sunday night, said she respects and understands the sheriff’s call for continued evacuations, and says that safety is the foremost issue, but she said she also feels frustrated.

“To be honest with you, there is a degree of frustration,” she said quoted by the SacBee. Asked whether it was a mistake not to have done more to improve the spillway earlier, she said she prefers to look forward.

“We are where we are,” she said. “We can learn from mistakes, things we failed to recognize. We have to move forward in a collaborative fashion and make sure this does not happen in the future. This is a learning experience for us.”

* * *

The California National Guard notified all its 23,000 soldiers and airmen to be ready to deploy, the first time an alert for the entire California National Guard had been issued since the 1992 riots in Los Angeles. So far their services have not been needed and the only incident to date came after Oroville police said they made one arrest and have identified a second suspect in connection with two looting crimes that occurred Sunday night.

Suspects smashed windows at a Dollar General and a liquor store, stealing alcohol and food. “Is it looting? That (term) probably does apply. We’re just calling it burglary,” Police spokesman Joe Deal said.

Otherwise, there have been few calls for service and few problems in town since the Sunday night evacuation call. Deal said 25 officers are on patrol, focused on residential areas and low-lying areas near the river. Oroville police are being supplemented by officers from the Orland police department, the CHP, and the sheriff’s department. Most calls Monday have been from people asking police to check on the welfare of relatives or friends.

* * *

But the biggest criticism facing officials is that the sudden decision Sunday to evacuate tens of thousands of people was a departure from earlier assurances, when officials had stressed the Oroville Dam itself was structurally sound. Unexpected erosion chewed through the main spillway during heavy rain earlier this week, sending chunks of concrete flying and creating a 200-foot-long, 30-foot-deep hole that continues growing.

Officials are most concerned about the dam’s emergency, earthen spillway that began taking on water after water was diverted from the main concrete spillway because of the damage. Engineers do not know what caused the cave-in. Chris Orrock, a Department of Water Resources spokesman, said it appears the dam’s main spillway has stopped crumbling even though it is being used for water releases.

The lake is a central piece of California’s government-run water delivery network, supplying water for the state’s Central Valley agricultural heartland and homes and businesses in Southern California.


This entry was posted in Uncategorized. Bookmark the permalink.