With National Treasures at Risk, D.C. Fights Against Flooding

The nation's capital is not exactly a beach town.  But the cherry-tree-lined Tidal Basin, fed by the Potomac River, laps at the steps of the Jefferson Memorial. And, especially since Superstorm Sandy, officials in Washington have a clear idea of what would happen in a worst-case storm scenario.

"The water would go across the World War II memorial, come up 17th Street," says Tony Vidal of the U.S. Army Corps of Engineers.  "And there are actually three spots where the water would come up where we don't have ... a closure structure right now."

Vidal is standing at one of those spots: the corner of 17th Street and Constitution Avenue, not far above sea level.  It's just a few blocks from the White House, though Vidal says that's protected by a slight rise in the land.  The U.S. Capitol is likewise protected — it is called Capitol Hill, after all.

But new flood maps in 2010 declared that the area between those two places, known as the Federal Triangle, is a flood zone.  It includes key government buildings like the Departments of Justice and Commerce, and the Internal Revenue Service.

Officials have long known the area was vulnerable and have been using sandbags for years.  But after 2005's Hurricane Katrina, the Army Corps deemed that approach no longer acceptable.  So it's been building a $10 million flood barrier at this corner.

With National Treasures at Risk, D.C. Fights Against Flooding