Congaree National Park earning designation as a Ramsar Wetlands of International Importance is like a three-star general getting a fourth star.

The Ramsar designation announced this week emphasizes the importance of a place already ranked as a national monument in 1976 (upgraded to national park in 2003), an International Biosphere Reserve in 1983 and a Globally Important Bird Area in 2001.

The Everglades is the only other U.S. national park on Ramsar’s list of nearly 2,000 important international wetlands. South Carolina now boasts two of the 31 U.S. sites. The Francis Beidler Swamp in Dorchester County earned Ramsar status in 2008.

“It is a true honor for Congaree National Park,” said park superintendent Tracy Swartout.

And to think, before the 1970s the southern Richland County area now so revered was just “the swamp” to generations of Midlands residents.

Technically, the 26,000 acres of Congaree National Park is mostly bottomland hardwood floodplain forest. Those biologically rich forests were common along rivers in the southeastern United States 200 years ago, but the park is the largest such forest remaining intact. The nearly 4,500 acres of never-timbered old growth forest at the heart of the park also ranks among the largest such tracts in the country.

“We have lost most of these communities to logging, agriculture and urbanization,” said Will Graf, a geology professor and floodplain ecologist at the University of South Carolina. “Congaree is by far the best and largest example of the community that is not a swamp — it is a dynamic, highly active floodplain connected to the hydrology of the river.”

The Ramsar list grew out of an international Convention on Wetlands in Ramsar, Iran, in 1971. To celebrate and protect the most important areas, the convention created strict criteria for inclusion on a list of wetlands significant not only for their home country but for humanity as a whole.

Park officials at Congaree first applied for the designation in 2003, but their application didn’t include all of the details the selection committee wanted. The application was resubmitted with the additional material gathered by Mark Kinzer in the park service’s Atlanta regional office and Bill Hulslander and Theresa Thom at Congaree, and the park made the list of 2012 additions.

The application points out that the rare forest houses many threatened or endangered species, animals such as the Rafinesque big-eared bat and the wood stork and plants such as Carolina bogmint. Another plus for the park is that it is well-protected, with much of it designated by the federal government as a natural area, with strict limits on development.

The Ramsar designation “shows that the park is of global importance, and that citizens as well as researchers can be confident of its significance in preserving valuable environments for future generations,” Graf said.

Park superintendent Tracy Swartout said many people think of national parks simply as places to visit and learn about nature or history.

“A lot of people don’t understand, parks can help improve the environment, too,” Swartout said.

Only a small portion of the park has trails with easy access for hikers. But about 90 percent of the park floods on average of once a year and much of it floods several times a year.

Swartout pointed out that those wetlands play a key role in flood prevention by absorbing and slowing the movement of flood waters, purifying and filtering surface water by trapping sediment and excess nutrients, replenishing groundwater and providing habitat for a wide range of plants and animals, including the old-growth trees for which Congaree was first recognized.

“Wetlands are vital to the health and wellbeing of the planet and its inhabitants,” Swartout said.