(OROVILLE, Calif.) — Water levels have reportedly started to fall at the Oroville Dam, where officials ordered nearly 200,000 people to evacuate to safer ground, as the country's tallest dam threatened to release uncontrolled floodwaters downstream.
Drivers jammed highways overnight and Monday morning as thousands of residents scrambled to flee the area.
Lake Oroville, which is located 75 miles north of Sacramento and about 25 miles southeast of Chico, is one of California's largest manmade lakes, and it swelled as a result of a month of heavy rains that battered the region.
Water began topping the emergency spillway on the 770-foot-tall dam Saturday, causing erosion damage that could lead to a surge of water being released, officials said.
Officials from California's Department of Water Resources said they planned to use helicopters to drop rocks to fill in the gouge in the spillway.
Residents of Oroville, Gridley, Live Oak, Marysville, Wheatland, Yuba City, Plumas Lake, and Olivehurst were all ordered to evacuate immediately, authorities said.
Butte County Sheriff Kory Honea said officials made the decision to nearly double the volume of water being released from the dam to stop erosion at the top of the auxiliary spillway.
"Hopefully, that will release pressure on the emergency spillway and they’ll find a repair to prevent a complete failure," Honea said Sunday. "[The] situation is dynamic and could change anytime."
California Gov. Jerry Brown issued an emergency order in response to the situation.
"The state is directing all necessary personnel and resources to deal with this very serious situation,” Brown said in a statement Sunday.
Moreover, the state's National Guard said it would provide eight helicopters to assist in reconstructing the emergency spillway.
The helicopters, along with two airplanes, will also be available Monday for search and rescue near the Oroville Dam, California National Guard Adjunct General David Baldwin said at a news conference Sunday.
He added that the California National Guard would be ready to deploy if needed.
The Mercury News, a local newspaper, reported that three environmental groups — the Friends of the River, the Sierra Club and the South Yuba Citizens League — filed a motion with the federal government in 2005 as part of Oroville Dam’s relicensing process, urging federal officials to bolster the dam's emergency spillway.
Within that motion, the groups warned that the dam did not meet modern safety standards, the Mercury News reported.
The Federal Energy Regulatory Commission rejected their request, the paper said.
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