The District faces serious potential problems from the Potomac River coming over its bank, failing urban drainage and storm surge flooding, according to a National Capital Planning Commission report.

A worst–case–scenario flood could turn the Jefferson Memorial into an island and flood the National Mall up to the Reflecting Pool, the report said. A warning came last June, when flooding from more than a foot of rain shut down five U.S. government buildings, forced the closure of several Smithsonian museums and left major roadways through the National Mall either off limits or in gridlock.