OROVILLE DAM, Tuesday 2PM: Evacuation order lifted; Reservoir levels continue to drop

Coverage from the press conference, 2/14/17 at 1pm:

KORY HONEA, Butte County Sheriff

“I want to begin by saying the actions of many dedicated caring and courageous people on the afternoon of February 12th, 2017 resulted in a victory on two fronts.  As a stark reminder, the forces of Mother Nature can create emergency situations requiring swift immediate action.  First, thousands of lives were protected from the looming prospect of a catastrophic failure of the emergency spillway by those who directed and facilitated the rapid and efficient evacuation of thousands of people and animals out of this area.  Second, while those evacuations were taking place, the loss or at least significant damage to the emergency spillway was prevented by those who directed the rapid reduction of the lake level to the point where water no longer ran over the spillway.  They also stopped the expansion of the massive hole that was developing in front of it.

The decisions made that afternoon were among the most difficult decisions that people charged with managing crisis situations are required to make.  Having the fortitude to take bold and swift action against uncertain rapidly developing situations, emergency situations, is required of those in charge of leading.

Evacuating the potentially affected areas gave the Department of Water Resources the time it needed to take the following actions:

  1. Reduce the level of the lake below the top of the emergency spillway so the erosion to the area in front of it could be halted.
  2. Deploy subject matter experts to the massive hole that was eroding in the area in front of the spillway so they could thoroughly inspect it. That inspection confirmed by those subject matter experts, from not only DWR but Army Corps of Engineers and FERC, revealed that there was no piping or other erosion that compromised the overall integrity of the emergency spillway.
  3. Increase the release through the primary spillway to 100,000 cfs in order to increase the capacity of the lake to accommodate future inflow expected because of the result of coming storms. This actions reduces the possibility that the emergency spillway will need to be used in the future.  This appears to be a reasonable and sustainable course of action as there has been no significant erosion along the east side of the primary spillway.
  4. Develop a plan to fortify the area in front of the emergency spillway against future erosion should its use become necessary in the future by lining it with boulders and concrete. This effort has commenced and is on pace to be completed ahead of future stormy weather.

As a result of these actions, the risks that we face when we initiated those evacuations has significantly been reduced.  Taking into account the current level of risk, the predicted strength of the next round of inclement weather, and the capacity of the lake to accommodate increased inflow associated with those storms, we have concluded that it is safe to reduce the immediate evacuation order currently in place to an evacuation warning.  This allows evacuated residents to return to their homes and for businesses in the area to resume operations.  An evacuation warning considers the possibility that future inclement weather or increased lake levels or problems associated with the existing damage to the spillway, could elevate risks in the future and necessitate immediate evacuations.  This is why residents need to be prepared to maintain situational awareness.  This reduction to an evacuation warning properly balances the need for people to resume their daily lives, well at the same time, being prepared to deal with future increased threats.

Butte County and the Department of Water Resources have put the public safety at the highest priority.  We’ll continue to monitor the situation very carefully and will take steps if necessary to assure public safety.

BILL CROYLE, Acting Director of Department of Water Resources

Right now, we are maintaining our releases from the reservoir at 100,000 cfs.  With the weather that we have been having over the last couple days, we continue to see the inflows to the reservoir drop.  Presently, as of noon today, our inflow is a little over 19,000 cfs.  What that means is the difference between the two means we’re continuing to make significant gains in removing water from the reservoir to drop the water surface elevation, further reducing the risk to our situation here and certainly to the emergency spillway.

We plan on continuing these releases.  I’m confident we can do that, based on a number of things. Our continuous 24/7 monitoring of the spillway itself which is the way that we’re moving water out of the system.  It has been stable for four days.  We were originally a few days ago at 55,000 cfs; because of the concerns that were raised, action was immediately taken to increase the flow up to 100,000 cfs.  With the stability of the spillway, we’re able to maintain those high flows.  Again, to make additional flood storage in the reservoir .. so with the runoff season, we can manage those inflows and the reservoir itself can absorb those higher flows …  What I want to say is we have a net discharge of 80,000 cfs out of the reservoir.

The elevation of the reservoir surface today at noon was 887 feet,  Our goal is to get down to what we call flood control storage which is an elevation of 850 feet.  We are continuously evaluating our ability to continue to remove water from the reservoir even lower as we deal with our emergency spillway to make sure we are arming and reinforcing that as well as continuously monitoring the spillway itself.

An important part of our monitoring and our response strategy is … assessments and reassements to make sure that we’re aware and prepared for any potential changes.  I want to reiterate that the spillway has been stable for four days.  That’s important for today and the coming days when we see small storms coming in, but really preparing also for the remainder of the wet season.

I want to talk a little bit about the storms coming in.  These storms are much smaller than we’ve seen here this last weekend.  The peak inflows with these storms are below the 100,000 cfs outflow that we have right now; in fact, they are far lower.  So what that means is we’ll see a little small increase in water surface elevation later this week, and I should say that with the existing releases, we should get down to the elevation of 850’ sometime late Saturday or Sunday assuming inflows continuously drop …

So with the storms coming in, we believe with the snow level dropping from 6000’ to 4000’ and these high flow rates, that will again make more storage and the next four storms should not approach any kind of threat towards the emergency spillway.

At the same time, I want to reiterate, we are aggressively attacking the erosion concerns that have been identified, but we’re committed to continue not only the concerns that have been identified, but subject to weather conditions, maintain continuous preventative actions to rebolster the area to the extent we would have to use that in the future.

We have a long spring runoff ahead of us, and we’re preparing for that by taking these additional actions; we continue to withdraw water from the reservoir, but also mitigate the potential to use that emergency spillway.  We think that as a whole, we’ve addressed the concerns we identified a few days ago, so we’re also moving to plan for continuous use as we move through this upcoming spring runoff season.

Thank you.

In other dam news today …

Oroville Dam:  Feds order California to design ‘immediate’ repairs: The federal government has ordered California to immediately design repairs to the Oroville Dam’s damaged primary and emergency spillways.  In a letter dated Feb. 13, the Federal Energy Regulatory Commission ordered the California Department of Water Resources to “initiate immediate design of emergency repair to minimize further degradation” of both structures, which have been eroding as water flows out of Lake Oroville this week.  The primary spillway, which technicians use to release water from Lake Oroville into the Feather River as the lake’s water level rises, has a concrete bottom that has had a “gaping hole” in its floor since Feb. 7, officials said. Technicians reduced the amount of water flowing down that spillway and the lake’s level kept rising. On Saturday, the lake reached capacity and water began to flow down a dirt hillside known as the dam’s “emergency spillway.” … ”  Read more from The Desert Sun here:  Oroville Dam:  Feds order California to design ‘immediate’ repairs

Trump reportedly keeping ‘a close eye’ on California dam crisis, White House says: President Donald Trump is “keeping a close eye” on the crisis at California’s Oroville dam, according to White House Press Secretary Sean Spicer.  “We hope everyone remains safe as the evacuations continue and we will be working alongside with FEMA and appropriate government entities to make sure that we are doing everything we can to attend to this matter,” Spicer said Tuesday at the White House news briefing.  Nearly 200,000 people have been evacuated out of fear of a catastrophic flood following damage to the emergency spillway at the dam. … ”  Read more from the Fresno Bee here:  Trump reportedly keeping ‘a close eye’ on California dam crisis, White House says

The latest pictures from the Department of Water Resources …

Excavators load rocks for helicopters to transport from the Oroville Dam parking lot, to the eroded site at the Oroville Dam auxiliary spillway in California, to help fight further erosion.

Boulders are being moved to fill erosion holes caused by the outflow of water from the Oroville Emergency Spillway when Lake Oroville reached 902 feet above sea level. The California Department of Water Resources continues to outflow 100,000 feet per second (cfs) of water from the Oroville Spillway, with the goal to lower the lake level by 50 feet to handle the next round of storms expected to hit Northern California in the next few days.

Florence Low / California Department of Water Resources

The latest drone video from Department of Water Resources …

For all coverage of the Oroville Dam Spillway incident on Maven’s Notebook, click here.

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