Federal officials are working urgently to strengthen the spillway at Prado Dam near Corona to prevent it from failing in a major flood, which could imperil hundreds of thousands of people living downstream in Orange County. After a May inspection determined the dam’s spillway could perform poorly in a major flood, the dam’s risk rating was changed from “moderate urgency” to “high urgency.” Dena O’Dell, a U.S. Army Corps of Engineers spokeswoman, said Thursday, May 16, that the agency is taking immediate measures to reduce the risk that the spillway will fail. And she said the agency was preparing to launch a project in 2021 to bolster the spillway and raise it 20 feet.