Evacuees might not go home until dam spillway is repaired

OROVILLE, Calif. — Nearly 200,000 people who were ordered to leave their homes after a California spillway threatened to unleash a 30-foot wall of water may not be able to return until significant erosion is repaired, authorities said yesterday.

The officials who issued the hasty evacuation order defended their decision, saying it was necessary to ensure public safety in the region downstream from the nation’s tallest dam, about 150 miles northeast of San Francisco. Engineers spotted a hole in the spillway, which they feared could have failed within an hour.

The water level of the massive reservoir known as Lake Oroville dropped yesterday, slightly easing fears of a catastrophic collapse. But with more storms on the horizon, crews raced to assess what happened and began dumping large boulders and sandbags into the spillway to prevent any more erosion.

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 fortifying 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.

“I’m not sure anything went wrong,” Bill Croyle said. “This was a new, never-having-happenedevent.”

Croyle and the local sheriff sought to reassure the public that downstream communities were safe until water began spilling over the lake’s edge Sunday and a chocolate-colored torrent of water began chewing through the slope below it.