"An evacuation warning means the immediate threat has ended but the potential for an emergency remains and therefore residents must remain prepared for the possibility of an evacuation order", Butte County Sheriff Kory L. Honea said.
Water authorities had been relieving pressure on the dam through the concrete-lined primary spillway last week, but lake levels rose as storm water surged in and engineers moderated use of the damaged primary spillway. They were right - for about the first 50 years. Officials hope to continue using a damaged main spillway to drain the lake another 37 feet in preparation for coming rain.
Fears of flooding from the nation's tallest dam, which reaches 770 feet, prompted evacuation orders for almost 200,000 people.
Windy conditions and more rain are forecast for Thursday.
Tens of Thousands of Californians Allowed to Return Home Around Dam
The evacuations were ordered Sunday after officials warned an auxiliary spillway of the reservoir - which allows the safe diversion of overflow water - was in danger of failure. Had workers caught the main spillway problems during the dam's last inspection in July 2015, this may have been averted.
Clay Church, a local Army Corps of Engineers spokesman, said he wasn't surprised that people were comparing Oroville and Lewisville Lake.
"We are working on those areas that have been challenged by the loss of a portion of the spillway".
The hillside was created to handle the "probable maximum flood", and annual dam inspections include a review of the spillway's structural integrity, according to a May 2006 filing by the Metropolitan Water District of Southern California. He said it has been stable for days and is handling those 100,000 cubic feet per second releases, which means they've been able to make a lot of room in the lake. "It's lovely, you want to go look at it", she said while folding clothes in the back of her pickup.
"They can't do the whole slope so the problem that developed before is still a possibility", Mount said. If the company had chosen to do proper maintenance after learning about the faulty floodway a decade ago, then 180,000 people wouldn't have been forced to evacuate. "I couldn't fit everything in my suitcase, so I just kind of brought it like that", Rorick said, pointing at the suitcase she was trying to organize on the bed of her pickup. If someone is staying with friends or family, they can visit Red Cross shelters during the day for information or a hot meal.
"When they have four or five trucks down there, the only thing they have to do is fill cracks", said Don Reighley, a retiree and fisherman who several times a week drives past the channel to launch his boat into the reservoir.