Flood at Great Falls 1996
Before and After photos of the Flood of 1996


FLOODING – Olmsted Island

On average, there is a major flood that overflows the banks of the Potomac River about every 12-13 years, causing it to rise over the banks of Great Falls. The waters of the Potomac River which made the C&O Canal possible also threatened it regularly. There was a destructive flood in 1829, only one year after construction on the canal begun. The flood of 1852 caused the river to rise 64 feet at Great Falls. While the storm of 1889, bankrupted the C&O Canal Company, the flood damage of 1924 proved too costly to repair, ending the commercial career of the canal.

Flooding continues to affect the Potomac River Valley. The largest flood on record hit in 1936. Most recently, the flood of 1996 caused extensive damage to the C&O Canal National Historical Park. Portions of the towpath and many structures needed to be rebuilt. In fact, along the boardwalk leading out to Olmsted Island, part of the railings are removable to reduce damage during major floods.

Flooding causes alterations. Flooding has changed the shape of the Potomac River since its ancestral times. It has also affected the growth of vegetation and can be seen in the trunk shape of many of the older trees. After being knocked askew during flooding, they resumed growing upward again, resulting in a kinked trunk. The power of water can even lift large stones and wash them down river, depositing them in geologically alien landscapes, like a fish out of water.

Discussion Questions: Flooding affects many people’s lives, whether they live along streams, rivers, or coasts. What can be done to reduce the harmful effects of flooding? What previous efforts have been successful & which ones haven’t? Why?

Trees affected by flooding
Kinked tree trunks caused by new growth following a flood

NPS / Nanette Nyce

Additional C&O Geology pages: Locks 15-20 | Olmsted Island | Devils Eyebrow | Purplehorse Beach | Pothole Alley | Widewater | Lamprophyre Dikes | Mather Gorge | Paw Paw Tunnel | Cumberland Coal

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Last updated: September 6, 2023

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