Among the63 U.S. national parks, few are as defined by a single river’s floodplain asCongaree National Parkin South Carolina.
While the features are also prominent inother parks, a full 80 percent of Congaree National Park lies within the Congaree River floodplain.
It’s a place home to one of the largest intact tracts of old-growthbottomland hardwood forestsin the United States.
In this image captured by theOLI onLandsat 9, the river winds through the forested plain, along with curving bands of green that trace old channels, ridges, and swales left behind as the river gradually migrated across it.
Slight differences in elevation in thesepaleochannelsand other landforms affect how frequently they flood, producing distinct ecosystems that appear in contrasting shades of green.
The river flows through flat, soft terrain, which encourages the formation ofbends and meanders.
Water typically flows faster on the outside of bends, leading to more rapiderosionas the channel carves into the outer riverbank.
It moves more slowly on the inside of bends, resulting in thedepositionof sediment and the growth of sandy features calledpoint bars.
Over time, this process can cut off a bend from the main river channel, forming U-shapedoxbow lakes.
The National Park ServicelistsWeston Lake, 1.2 miles from the visitor center, as one of the park’s most permanent oxbow lakes, noting that it is relatively deep and lacks the shallow clay and silt layer found in most of the park’s other oxbow lakes, such asDevil’s Elbow.On the right side of the image isBates Old River,a roughly 4-mile-long abandoned channel of the Congaree River and one of the longest oxbow lakes in South Carolina.
Over time, abandoned channels and oxbow lakes can fill with sediment and become shallow wetlands.
Some of these low-lying, water-filled features are known assloughs, where flood-tolerantcypress-tupelo foreststend to grow.
While loggers targeted forests along the Congaree in the 1880s, challengessuch as frequent flooding, interminably muddy roads, and mosquito-plagued conditions meant that most of the floodplain forests escaped the widespread logging that transformed other parts of the Southeast.
By the 1950s, conservationists had begun to recognize how rare old-growth forests of this type had become in the region.
Congress designated the area a national monument in 1976, and it became a national park in 2003.
As the river snakes its way through the park’s mostly flat terrain, it overflows its banks several times per year, usually in the winter and early spring but also in the summer and fall after hurricanes and major rainstorms.
These floods distribute broad layers of nutrient-rich silt throughout the floodplain, nourishing the forests and contributing to the high concentration of unusually large trees in the park.
Over the decades, Congaree National Park has harbored a remarkable array of giant“champion” treesthat have held national and state size records for their species.
Though individual trees have gained and lost champion status as they have been damaged, have died, or been surpassed by newly measured trees elsewhere, Congaree trees such as the possumhaw, water hickory, loblolly pine, laurel oak, swamp tupelo, and sweetgum have held records at times.
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NASA Earth Observatory image by Michala Garrison, using Landsat data from theU.S. Geological Survey. Story by Adam Voiland.
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American ForestsCongaree: Where The Trees Are Still Tall. Accessed August 27, 2026.
Atlas ObscuraHow One Biologist Drew a Hyper-Accurate, Ranger-Approved Map of Congaree National Park. Accessed August 27, 2026.
Discover South Carolina, Champion Trees are Star Attraction at Congaree National Park. Accessed August 27, 2026.
National Parks Conservation AssociationCongaree: ‘Champion’ Trees, Synchronous Fireflies and More. Accessed August 27, 2026.
National Parks Conservation AssociationThe Wild Congaree. Accessed August 27, 2026.
National Park Maps, Congaree Forest Map. Accessed August 27, 2026.
National Park Service, Last Stand for Floodplain Forests. Accessed August 27, 2026.
National Park Service, Congaree National Park. Accessed August 27, 2026.
National Park ServiceCongaree National Park: Geologic Resources Inventory Report. Accessed August 27, 2026.
U.S. Environmental Protection Agency, Bottomland Hardwoods. Accessed August 27, 2026.
U.S. Geological SurveyEcology of Congaree National Park. Accessed August 27, 2026.
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