Crews worked into the night Wednesday to shore up the emergency spillway at troubled Oroville Dam, racing to fortify the structure before the next series of storms, the first of which was forecast to hit before midnight.
Three storm systems will move into Northern California during the next six days, according to the National Weather Service. The first system will drop about an inch of rain in the Oroville area between 10 p.m. Wednesday and 4 p.m. Thursday. Greater amounts of precipitation will fall in the mountains northeast of the reservoir.
Forecasters are confident that the first two storm systems will not cause huge inflows into Lake Oroville. They are less confident about the third system, which is due sometime Tuesday. That storm could be bigger and warmer, meaning more rain and snowmelt streaming into the swollen reservoir.
“The third wave is looking like our problem child,” said Michelle Mead, a warning-coordination meteorologist at the National Weather Service in Sacramento.
Oroville Dam, about 65 miles north of Sacramento in Butte County, holds the state’s second-largest reservoir and serves as a crucial flood-control structure for the eastern Sacramento Valley.