#California grapples with eroding dam; emergency spillway gets first-ever use

OROVILLE, Calif. (AP) — The Latest on storms crumbling the spillway of California’s second-largest dam (all times local):

7 a.m.

State officials say water could pour over an emergency spillway at Lake Oroville for the first time ever, a last-ditch alternative that they had been hoping to avoid.

The California Department of Water Resources says that the reservoir’s emergency spillway likely will be used, perhaps, as soon as early Saturday.

Earlier this week, chunks of concrete flew off the nearly mile-long spillway, creating a 200-foot-long, 30-foot-deep hole. Engineers don’t know what caused the cave-in that is expected to keep growing until it reaches bedrock.

The department does not expect the discharge from the reservoir to exceed the capacity of any channel downstream as the water flows through the Feather River, into the Sacramento River and on to the San Francisco Bay.

Officials say Oroville Dam itself is sound and there is no imminent threat to the public.

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1:55 a.m.

A gaping hole in the spillway for the tallest dam in the United States has grown and California authorities said they expect it will continue eroding as water washes over it but the Oroville Dam and the public are safe.

Earlier this week, chunks of concrete flew off the nearly mile-long spillway, creating a 200-foot-long, 30-foot-deep hole. Engineers don’t know what caused cave-in that is expected to keep growing until it reaches bedrock.

But faced with little choice, the state Department of Water Resources resumed ramping up the outflow from Lake Oroville over the damaged spillway to keep up with all the runoff from torrential rainfall in the Sierra Nevada foothills.

Officials said the critical flood-control structure is at 90 percent of its capacity. But the dam is still safe and so are Oroville’s 16,000 residents.