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

itoggle caption 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

itoggle caption 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

itoggle caption 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

itoggle caption Dan Levine /EPA /LANDOV