Helicopters dropped giant rock-filled sandbags into place Monday to shore up a California reservoir that had threatened to breach its banks and unleash a 30-foot wall of water, but officials said an evacuation order covering nearly 200,000 people would stay in place until they are sure it’s safe to return home.
Officials defended their decision to issue the hasty order to abandon homes downstream from the nation’s tallest dam, about 150 miles northeast of San Francisco. They said it was necessary for public safety after engineers spotted a hole in an emergency spillway, which they feared could have failed within an hour.
The acting head of the state’s Department of Water Resources said he was unaware of a 2005 report that recommended reinforcing the earthen emergency spillway with concrete for just such an event. The spillway had never been used in the dam’s nearly 50 years of operation, and it was not near capacity when it began to fail.
Chaos ensued as anxious residents rushed to pack up their families and abandon several communities in Butte, Yuba and Sutter Counties. The flat northern Central Valley is known mainly for its abundant agriculture, which is fed by dammed-up rivers that tumble down through the Sierra Nevada foothills.
It took some people seven hours to travel to evacuation centers that should have been an hour away, said Chico Councilman Andrew Coolidge, who visited with evacuees in packed shelters in his city.
However clueless Butte County Sheriff Kory Honea insisted the evacuation had been accomplished in a “fairly timely fashion” and a “fairly orderly manner.”
Environmental groups raised concerns years ago about the stability of the emergency spillway, but state and federal officials dismissed them and insisted the structure was safe, according to records.
In 2005, three advocacy groups complained to the Federal Energy Regulatory Commission that using Lake Oroville’s earthen spillway would cause significant erosion because it was not armored with concrete.
They said soil, rocks and debris could be swept into the Feather River, potentially damaging highway bridges and power plants. The groups warned of a complete failure of the dam itself, threatening lives and property.
Nearly three years later, state officials said no “significant concerns” about the emergency spillway’s integrity had been raised in any government or independent review.
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