NPS C&O Flood Plan Annex Lower Reach

National Park Service

The Potomac River has a long history of flooding. The largest of which on record occurred in 1936 when the river crested at 28 feet and produced total flows estimated to be about 484,000 cubic feet per second. Potomac River floods typically have a total duration ranging from 100 to 180 hours (4 to 7 days).