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 around 188,000 people would stay in place until they are sure it's safe to return home, the AP reports. It is possible that the crisis could continue for weeks, reports the San Francisco Chronicle. 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 water level of the massive reservoir known as Lake Oroville dropped Monday, slightly easing fears of a catastrophic collapse. But with more storms on the horizon, crews raced to fortify heavily eroded soils where water flowed over the edge of the reservoir and carved huge channels in the earth as it gushed toward the Feather River. The acting head of the state's Department of Water Resources said he did not know if anything had gone wrong and 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. "This was a new, never-having-happened-before event," Bill Croyle said. (Read more Oroville Dam stories.)