OROVILLE >> Evacuation orders for 200,000 people in communities downstream of the Oroville Dam were lifted Tuesday afternoon, when officials announced they did not think the broken spillways presented an immediate danger.
It ended a three-day, two-night ordeal for an exodus of residents along the Feather River, who were told Sunday afternoon that a rupture of the emergency spillway was imminent. Such an event would send a 30-foot-tall wall of water hurtling downstream, first hitting Oroville and eventually flooding Yuba City, 30 miles to the south.
The reduction of the order to an evacuation warning was announced at 1:45 p.m. It means that people can return to their homes and businesses, but are asked to remain vigilant should conditions change for the worse.
Butte County Sheriff Kory Honea said the lake level had dropped to where it was no longer posed a threat of going over the emergency spillway.
He added that an inspection of the hole that was created by water coming over the rim on Sunday revealed “no hiking erosion that compromised the overall integrity” of the spillway.
In addition, the emergency spillway has been fortified against future erosion and there’s a “reasonable sustainable course” of letting high volumes of water out of the primary spillway that reduces the need to use the emergency spillway in the future.
Officials added that this week’s incoming storms are not expected to lift the lake’s level significantly.
“As a result of these actions, the need for evacuation has been significantly reduced,” Honea said. “Looking at the current level of risk, and the predicted strength of the next round of storms and the capacity of the lake to accommodate the rain, we have concluded that it is safe to reduce the order to an evacuation warning.”
Tuesday at 9 a.m., the lake’s level had dropped to 888.68 feet, about 12 feet below the Oroville Dam’s capacity of 901 feet. State water officials are continuing to release water through the primary spillway at a flow rate of 100,000 cubic feet per second, or about 748,000 gallons per second.
With the first in a series of storms expected to hit the Oroville area on Wednesday night, bringing as much as 8 inches of rain through Monday, authorities are reducing the level of Lake Oroville as quickly as possible.
Bill Croyle, acting director of the Department of Water Resources, said his department is trying to lower the lake by 50 feet.
Meanwhile, the unexpected vulnerability of homes and buildings in the evacuated areas have given rise to unrest and scattered lawlessness. The Chico-Enterprise Record and Oroville Mercury Register reported Monday night that authorities are dealing with a handful of break-ins reported in the first 24 hours of the evacuation order.
Oroville police Lt. Gil Zarate said thieves have broken into a few homes as well as commercial properties, including Dollar Tree on Sunday night and Tony’s Liquor Store and Nick’s Stuff N Things on Monday. Police arrested a vandal at Tony’s Liquor Store, Zarate said.
Police had been faced with monitoring empty residences and businesses as well as stopping pedestrians and asking them to leave the low-lying areas of the city, including the downtown and near the Feather River, he said.
The main spillway partially collapsed last week when a huge hole wore through the concrete. State water officials slowed releases through that spillway after the water, looking like Niagara Falls, carved a section of hillside away toward the main face of the 770-foot-tall Oroville Dam.
But the lake’s waters continued to rise, which sent water over the top of the emergency spillway, a dirt embankment topped with a lip of concrete, for the first time in the dam’s 49-year history. The heavy flow of water coming over the lip was washing away the dirt on the normally dry side, and officials feared that could eventually undercut the concrete, causing it to fail.
Using trucks and helicopters, work crews are moving large rocks and gravel to fill erosion on the emergency spillway, according to state water officials. The emergency spillway and primary spillway are continuously being inspected and evaluated for further erosion.
Staff writers Paul Rogers and Matthias Gafni contributed to this report.
