OROVILLE (CBS13/AP) – Officials scrambled Wednesday to drain more water from a lake behind battered Oroville Dam before new storms hit Northern California and test the quick repairs made after water cascaded down an unpaved spillway and prompted a massive evacuation.
Three storms were expected, starting Wednesday evening and stretching into next week.
California Department of Water Resources officials said the reservoir was draining fast enough to handle the storms.
Still, officials warned residents who have returned to their homes to remain vigilant.
“There is the prospect that we could issue another evacuation order,” Butte County Sheriff Kory Honea has said.
National Weather Service forecaster Tom Dang said the first two storms were expected to be light. The first could bring 2-3 inches of rain Wednesday followed by an even smaller accumulation from the second storm.
However, the third storm, starting as early as Monday, could be powerful.
“There a potential for several inches,” Dang said. “It will be very wet.”
Dump trucks and helicopters dropped thousands of tons of rocks and sandbags to shore up the spillways over the weekend and avoid what could be a catastrophic failure and flood.
Some 200,000 people living downstream of the dam were allowed to return home Tuesday after being ordered to evacuate Sunday.
The swollen lake reached its capacity over the weekend and spilled down an unpaved emergency spillway for nearly 40 hours, leaving it badly eroded. The problem occurred six days after engineers discovered a growing hole in the dam’s main concrete spillway.
Bill Croyle, acting chief of the water department, said the main spillway has been stable over the past four days and is handling a large flow of draining water.
It’s unlikely the lake will reach capacity again, he said, but if it does the emergency spillway should be able to handle the overflow.
Croyle said teams were working on plans for permanent repairs to the dam’s main spillway that could cost as much as $200 million.
Long-term repairs will likely begin after the spring runoff, when crews can close floodgates for an extended period without the lake refilling with melting snow.
Meanwhile, crews were fortifying the adjacent emergency spillway, where erosion threatened to undermine its concrete wall atop the structure.
Late Tuesday, President Donald Trump ordered federal authorities to help California recover from severe January storms – a disaster declaration that also assists state and local officials with the dam crisis.
State officials were on the defensive about their decision to call for mass evacuations Sunday, just a few hours after saying the situation was stable.
The order forced families to rush to pack up and get out.
Sheriff Honea said the decision protected lives and bought time for water experts to address the problems.
But evacuees grew weary after two days away from home and welcomed the news that they could return while staying vigilant.
Rod Remocal said he and his wife would now be ready to leave their Biggs home near the dam at a moment’s notice after fleeing in a rush Sunday.
“We’re all coming back and pack and be ready this time,” Remocal said. “This time we’re going to be on call like they said.”
Copyright 2017 The Associated Press.