188,000 Evacuations from California Oroville Dam Spillway
Water poured over the emergency spillway at the Oroville Dam in Northern California for the first time in 50 years. The main spillway was damaged during the storms this past week. But the emergency spillway had erosion that threatened to cause a collapse that would have affected hundreds of thousands of people…so they were evacuated.
A collapse of the spillway would have sent a 30 foot “wall of water” crashing down on communities in the Feather River Basin.
The traffic snarls were unreal as at least 188,000 people were evacuated from Marysville, Yuba, Sutter, and Butte counties. As of this morning, the threat of imminent collapse lessened, but the evacuation order remained in effect. The spillway is being monitored.
The emergency spillway at the Oroville Dam had not been used in 50 years. The State of California has been working place rocks over the spillway that is eroded. Helicopters were used to drop the rocks in places to prevent a collapse.
Overnight, the level of water in Lake Oroville dropped, and water over the auxillary spillway ceased, so the danger lessened significantly.
“A hazardous situation is developing with the Oroville Dam auxiliary spillway. Operation of the auxiliary spillway has led to severe erosion that could lead to a failure of the structure. Failure of the auxiliary spillway structure will result in an uncontrolled release of flood waters from Lake Oroville.
In response to this developing situation, DWR (Department of Water Resources) is increasing water releases to 100,000 cubic feet per second.
“Immediate evacuation from the low levels of Oroville and areas downstream is ordered.” Sheriff’s press release
The evacuation order remains in effect for now, even though the water level has significantly receded.
“There is still a lot of unknowns. We need to continue to lower the lake levels and we need to give the Department of Water Resources time to fully evaluate the situation so we can make the decision to whether or not it is safe to repopulate the area.” Butte County Sheriff Kory Honea