17th Street between Constitution Avenue, Northwest, and Independence Avenue, Southwest, will close from 4 AM to 4 PM on Tuesday, October 6. It’s the annual test of the 17th Street Levee, a flood-control measure that’s meant to protect Federal Triangle from catastrophic flooding.
The levee comprises aluminum panels and steel posts that complete a stone wall you can see on the Washington Monument grounds. The gap was originally closed with sandbags, but following dramatic flooding in June 2006 that knocked out electricity at the National Archives and caused $13 million worth of damage to the IRS building.
The Army Corps of Engineers determined the following year that the then almost 70-year-old system to block 17th Street with sandbags was “unreliable”; the new levee was completed in 2014. The current levee is “capable of holding back waters up to 19 feet above sea level,” Elliot Carter wrote in a cool piece about the levee for Atlas Obscura. “They’re stored ready to go on trucks in Bladensburg and can be assembled in a few hours.”