By Holly Yan, Paul Vercammen and Steve Almasy, CNN
OROVILLE, California — With the water level at California’s Lake Oroville dropping, authorities lifted mandatory evacuations, allowing tens of thousands of residents to return to homes near the reservoir’s dam.
But Butte County Sheriff Kory Honea on Tuesday cautioned residents and business owners to “maintain situational awareness” with a series of storms forecast for later in the week.
“People who have special needs or require extended time to evacuate should consider remaining evacuated,” the sheriff said.
The pressing problem is with the emergency spillway, which lets excess water out when the lake level gets too high, at 901 feet. On Tuesday, Lake Oroville was down to 887 feet, 37 feet above where officials want it to be.
Workers rushed to shore up the emergency spillway with boulders and concrete. They dropped huge white bags stuffed with rocks, as well as chunks of concrete. Dump trucks and cement mixers shuttled material to the damaged spillways.
Bill Croyle, the state’s acting director of water resources, believes with the work done to increase outflow and less rainfall expected than in previous storms, the emergency spillway won’t be needed.
“We have addressed the issue … but will continue to increase our mitigation measures to increase its ability to handle a high-water event,” Croyle told reporters.
Help from the air
Helicopters have been dropping bags of rocks into the gouged portion in an effort to plug the hole.
“Our crews are working around the clock, 24/7, to try to get as much rock as possible onto the damaged spillway before the next storms come,” Cal Fire spokesman Josh Janssen said.
“We are feeling positive,” said Al Duncan, spokesman for the response team.
Janssen said the lake level has been dropping about a foot every three hours — and that rate could improve.
“Lakes are shaped like funnels, so we could see the water level start to drop faster,” he said.
More rain expected
The next wave of rainfall will come overnight Wednesday into Thursday, CNN senior meteorologist Dave Hennen said. A series of storms will follow and last through the weekend.
Rainfall over the next week could total 5 to 12 inches and will likely push hundreds of billions of gallons of water back into Lake Oroville, Hennen said.
Request for federal aid
Gov. Jerry Brown said Monday that the state is “doing everything we can to get this dam in shape so (evacuees) can return and live safely without fear.” Brown said he had requested federal response aid.
White House press secretary Sean Spicer said President Donald Trump “has been keeping a close eye on the Oroville Dam situation in California.”
He did not say whether Trump has been in touch with Brown, but said the administration has been communicating with Republican Rep. Doug LaMalfa and other state officials.
“We’ve worked closely with Doug LaMalfa, who represents California’s first district where the dam is located, and other state officials to help people who have been impacted,” Spicer said Tuesday.
“The situation is a textbook example of why we need to pursue major infrastructure package in Congress. Dams, bridges, roads and all ports around the country have fallen into disrepair. … 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.”
Tallest dam in the US
The Oroville Dam, the tallest dam in the United States, provides flood control for the region. The dam itself has no structural issues, but the two spillways that release water from the lake to prevent overflow have structural problems.
The main spillway, which is lined, or paved, has a hole almost the size of a football field and at least 40 feet deep.
It’s being used to drain the lake at a rate of 100,000 cubic feet per second in an effort to reduce the water level. Normal flows down the main spillway are about 55,000 cubic feet per second.
The emergency spillway, which is an embankment covered with trees, is a last resort and was used for the first time in its 48-year history on Saturday. Lake water began washing into it this weekend and prompted the evacuation order when officials noticed damage on the spillway.
How did we get here?
Questions remain over how it got to this point at Lake Oroville. Why weren’t more efforts made to prevent spillway erosion after concerns were raised more than 10 years ago?
Croyle said he was “not familiar with 2005 documentation or conversation” about spillway concerns and emphasized the efforts underway to understand the current dynamics of the dam.
“We’re going to continue to work on the challenges we have,” he said.
The governor defended the state’s flood infrastructure Monday and said he welcomed “more scrutiny” as efforts continue.
Oroville as a ghost town
After the evacuations, downtown Oroville remained a ghost town. Stores sat dark and empty with sandbags stacked in front of doors. Empty gas stations had yellow tape ringed around the pump to indicate there was no more fuel.
All schools in Sutter and Yuba counties have been closed. Affected schools in Butte County are shut until Friday.
RaeLynn Jones and her fiance, who had fled their Oroville apartment near Feather River on Sunday, came back to their home Monday to pick up more of their items.
She noted that her building was unscathed, but at Feather River, the water level nearly reached the treetops. Surrounding playgrounds, gazebos and sports fields were completely submerged, she said.
Jones is staying at her fiance’s home, which is on higher ground. Nine people and three dogs are sharing the house where they’re riding out the evacuation order. With everything closed, they’re eating whatever is left in the kitchen and snacks from the gas station. For now, all they can do is wait.
Paul Vercammen reported from Oroville and Holly Yan and Steve Almasy reported and wrote from Atlanta. CNN’s Emanuella Grinberg, Eliott C. McLaughlin, Madison Park, Carma Hassan and Kayla Rodgers contributed to this report.