The Department of Water Resources declined to answer specific questions about the fix work, saying engineers were focused on ensuring public safety.
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When reservoirs get too full, their operators release extra water down long channels, or spillways, created to carry it downstream and into safety.
The crisis peaked Sunday, when engineers found the pocket of erosion under the emergency spillway – a concrete wall built to permit overflow when Lake Oroville hits capacity.
“Obviously any rain this week is not helpful at all”, he said.
The area was bracing for another onslaught of storms forecast to begin Thursday, but the temperature is now projected to drop, which will diminish rains and lessen the flow into the reservoir. “Without power lines to carry electricity into or away from the power plant and its outlets, the plant outlets would be unable to discharge at a capacity of 14,000 cfs”, a February 10 press release from the DWR stated.
Croyle said officials are also monitoring the watersheds and preparing for future runoff.
Meanwhile, federal regulators have told the dam’s managers at the state water resources department they must enlist a group of “independent consultants” to assess what went wrong and how to make long-term repairs.
“If the land gets too wet we can’t operate heavy machinery out there, and it could become a safety issue with our personnel out there”, Orrock said. “It’s kind of like a war zone for all the right reasons out there”.
DWR must submit its picks for board members, a forensic team, and a plan and schedule for both to federal officials by Saturday.
Dam operators are expecting the storm to deliver inflows of 40,000 to 60,000 cubic feet per second; outflows over the main spillway will be kept at 100,000 cfs, assuming the structure holds.
The California Department of Water Resources had indicated that the water level was dropping at eight to 10 centimetres per hour.
“We continue to armor up the hillside”, Orrock said.
The Hyatt Powerhouse underneath the dam, which can release about 13,000 cfs, remained out of operation, Orrock said. He added that the power plant is usually shut down when releases down the main spillway reach 60,000 cfs. “Every time they said something, they turned around and said something different”.
Butte County Sheriff Kory Honea announced Tuesday evening he was lifting an evacuation order issued on Sunday, Dan Brekke of member station KQED reported.
But, the sheriff said, the region would remain under an evacuation warning, meaning that residents need to be ready to flee again if conditions worsen.
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As evacuation orders remain in effect for almost 200,000 persons, the U.S. Defense Department says it stands ready to assist in operations surrounding a failing dam in northern California.
