The Cahaba: A River of Riches- page 3 | Science | Smithsonian
The 190-mile-long Cahaba River is home to many rare species, some of which were thought to be extinct. The showy Cahaba lily (at Halfmile Shoals) thrives in clean, clear, rapidly flowing water. (Beth Maynor Young)

The Cahaba: A River of Riches

An unsung Alabama waterway is one of the most biologically diverse places in the nation, home to rare flora and fauna

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"You'd see schools of fish literally banging their snouts on the face of the dam, trying to travel upstream," says Paul Freeman, an aquatic ecologist for the Alabama chapter of the Nature Conservancy. Once a popular angling spot, the area upstream of the Marvel Slab had lost most of its fish population.

Throughout the country, small, outdated dams and other river barriers like the Marvel Slab are coming down. Many are no longer needed for their original purposes and have become safety hazards, environmental disasters or both. Their removal can jump-start river restoration and has yielded prompt and dramatic results in Maine, Florida, Arizona and elsewhere. But in Alabama, no dam had ever been removed for environmental reasons. Freeman and other supporters of the idea spent five years politicking in local communities and collecting the necessary bureaucratic approvals.

In 2004, the federal Army Corps of Engineers—the agency with authority over the Marvel Slab—and a host of other private and public agencies finally got the go-ahead. Biologists in wet suits and waders, armed with nets and plastic buckets, spent three days moving more than 12,000 snails and mussels out of the way, then donned hard hats to watch the removal of the slab. Though "all the guys really wanted to blow up the dam," says Wendy Smith of the World Wildlife Fund, construction experts recommended it be picked apart with a heavy-duty jackhammer. Doing so uncorked the longest free-flowing stretch of river in Alabama.

The results were dramatic. "The fish came back within hours, and the snails came back within days," says Freeman. Each summer since, Freeman and his colleagues have snorkeled at the former slab site, counting snails and mussels. In the past two years, the crew found as many as 2,000 snails per square meter in some places, up from only a handful or none at all before the removal. They have also documented a jump in native mussels. "Life rebounds pretty quickly when you give it a chance," says Freeman.

After discussions with Freeman and other biologists, officials from the Army Corps recently agreed to change the management of the two remaining river barriers between Birmingham and the Gulf of Mexico. This past spring, the Corps began opening and closing the locks on the Alabama River on a schedule designed to allow more native migratory fish to return to the Alabama and Cahaba rivers.

That could help a fish that is one of the rarest vertebrates in North America: the Alabama sturgeon, which resembles a small shark with whiskers and was once found in rivers throughout the area. In the spring of 2007, biologists were thrilled to find a lone sturgeon on the Alabama, the first seen in nearly seven years. They hoped it was a female, which they would be able to breed using stored sturgeon sperm, but it turned out to be a male. The biologists implanted a tag in it and released it back into the Alabama, where it lives today—one of the last of its kind.

Below the Marvel Slab site, the Cahaba continues its course southward toward the Alabama River. Its murmurs grow even quieter and its bends more generous, looping over the coastal plain. Cypress trees, their fluted buttresses punctuated with knobby "knees," line its banks, and the air fairly sags with moisture. Here, old river oxbows become steaming swamps, hung with Spanish moss and home to carnivorous plants and the occasional alligator.

This tropical stretch, far from Birmingham and other cities, is even less traveled than the lily shoals, and even experienced canoeists and anglers can trip up on the unknown. On one of his first dates with his future wife, Shannon, Haddock suggested an exploration of the Oakmulgee, a Cahaba tributary. The stream turned out to be so overgrown and littered with fallen logs that the pair traveled in circles, managing to escape only after a marathon bushwhack. "I couldn't believe she was still speaking to me the next day," Haddock says.

Like the rest of the river, the lower Cahaba burgeons with diversity. Fish dart underneath canoes, and a few handfuls of river mud can contain a foot-long washboard mussel or a tiny, delicately striped fawn's foot mussel. Fish throughout the Southeast have endearingly quirky common names, and those here are no exception. "There's a frecklebelly madtom, a freckled madtom, a speckled madtom, a speckled darter and a freckled darter," Haddock singsongs. "But there's no frecklebelly darter."

The lower Cahaba also winds through history. It passes near the Edmund Pettus Bridge, which crosses the Alabama in Selma and is infamous as the site of a 1965 clash between police officers and unarmed civil rights demonstrators. The Cahaba ends at the remains of Old Cahawba, the state's first permanent capital. During the cotton boom on the surrounding prairies, Cahawbans built fine mansions—including the then-largest in the state—on broad streets named Mulberry, Pine, Oak and Chestnut. Ferries operated on both the Cahaba and Alabama rivers, and in the wet season, even steamboats made their way up to the Cahaba Valley.

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