Marine One, carrying President Obama, takes an aerial tour of Oso, Wash., on Tuesday. The president made a brief stop in the area devastated by last month's mudslide. Carolyn Kaster/AP hide caption

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Carolyn Kaster/AP

A destroyed house sits in muddy debris near Oso, Wash., on Sunday. A rain-soaked hillside let loose a wall of mud Saturday, inundating neighborhoods along the Stillaguamish River's North Fork. Lindsey Wasson/AP hide caption

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Lindsey Wasson/AP

Divers found a 2-inch-wide crack at the bottom of the fourth spillway pier from the left in this photo of the Wanapum Dam. Grant County Public Utility District hide caption

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Grant County Public Utility District

The scene near Mount Vernon, Wash., on Thursday after part of an Interstate 5 bridge collapsed into the Skagit River. Dan Levine /EPA /LANDOV hide caption

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Dan Levine /EPA /LANDOV