In 1812 President Thomas Jefferson sent Captain Amos Stoddard to explore the Louisiana coastal plain, including the Atchafalaya Basin. He was one of the first to describe the strings of lakes and bayous that laced together the Atchafalaya Swamp, which divided the “Delta from what is called the elevated country.”
From thirty miles below Old River, “the Chafalia affords a beautiful sheet of water, at least as far down as Cow island, from seventy-five, to one hundred and fifty yards wide, and from twenty-five to thirty feet deep in the dry seasons. At Cow island the stream is divided; one part spreads into a large lake; the other part continues its course, and seems to maintain its usual breadth and depth. The current of the Chafalia is gentle till it is joined by the Plaquamines about one hundred fifty miles from the outlet on the Mississippi, which its velocity is considerably increased. It communicates with lake Natchez by means of several bayous, the largest of which is bayou Long. This bayou is connected with lake Flat, Grand river, and Grand lake, by means of several bayous, most of which are navigable in the season of high water. Grand lake is about forty miles long, and from three to ten miles wide, into which the Chafalia is emptied by a channel of about two hundred fifty yards wide; and a depth of nearly forty feet. It then posses through Berwick bay, which is from half a mile to two miles wide, and from sixty to eighty feet deep; and after a course of about twelve miles, it falls into Vermillion bay, which is an arm of the gulf.”–Captain Amos Stoddard
In 1982 the Corps of Engineers issued its Final Environmental Supplement, its plan for the Atchafalaya Basin. This came only after a multi-year battle with those people who cherish the Atchafalaya River Swamp and did not want to see it stripped of its trees, drained, and turned over to agriculture. The plan forbad the conversion of the swamp to other uses, including agriculture, and it banned certain logging practices.
Another source of concern for the Atchafalaya environmentalists was the huge amount of sediment being deposited in the lakes that compose the river swamp. The process began as the Atchafalaya drew more and more water and sediment from the Mississippi and from the Red River. Until 1917 the lower two-thirds of the Atchafalaya Basin was an open freshwater lake. Between 1917 and 1930 the Atchafalaya deposited 4.63 square miles of sediment into Grand Lake at its head and continued to do so at the rate of three-fourths of a square mile per year. By 1989 the process of sedimentation reduced the great basin lake, which once covered 230 square miles, to series of small shallow lakes—Six Mile Lake, Upper Grand Lake, Lower Grand Lake, and others—which cover fifty square miles at the basin of the basin north of Morgan City.
Which brings us to the Flood of 2011. Yesterday, the U.S. Geological Survey issued a press release noting that this flood increase the rate of sedimentation in the swamp. It will erode some parts of the basin just below the Morganza Spillway and deposit sediment in cypress-tupelo swamps that are normally isolated from the process of sedimentation.
Willows, the pioneers species on new soil, took root on the edge of Des Ourses Swamp, one of the many lakes in the Atchafalaya river swamp. The wetland and its surrounding forest swamp are a birding paradise. Ducks–mallards, woodies, gadwalls, shovelers, pintails, wigeons, teals, mergansers, and ring-neckeds–spend the winter. Wading birds–stilts, yellowlegs, sandpipers, dowitchers–stalk the shallows. Plovers, killdeers, sandpipers, and snipes pick their way through the mud flats in July when the impoundment is drained. American woodcocks fly in at dawn and dusk. Kites–swallow-tailed and Mississippi, red-shouldered-hawks, barred owls, woodpeckers–downy and red-bellied loggerhead shrikes, Carolina wrens, gnatchatchers, warblers, and oriole inhabit the forest, joined in the winter by kestrels, kingfishers, phoebes, kinglets, thrushes, robins, sparrows–field, song, white-throated, and white-crowned, and warblers–orange-crowned and yellow-rumped.[i]
The banks of a narrow slough between Upper Grand River and Upper Flat Lake are lined with willows and carpeted with cockleburs. Depending on the water level, sometimes the slough flows to the lake and sometimes it flows to the river. Sometimes, it is flooded, and sometimes no more than a muddy ditch, too thick to paddle a canoe in and too wet to walk in.
Within the Lower Atchafalaya Floodway there were 94,000 acres of pioneer forests on recently deposited sands when the 1982 plan was issued. Nearly pure stands of willow could be found on new deposits. Older deposits hosted a mix of willow, cottonwood, and sycamore, with waxmyrtle, false nettle, lizard’s tail, blackberry, shield fern, and swartweed growing in the understory or covering the ground. The willow forests provided habitat for deer, swamp rabbits, and migratory songbirds.
As more and more sediment accumulated and the land dried out, the pioneer forests would evolve into productive bottomland hardwood forests, treed in oaks–water, willow, Nuttal, and overcup; pecans, ash, and red maples: habitat for wildlife, gold to the timber industry. Without the 1982 plan the bottomland forests would have been logged and the land turned over to agriculture. The plan forbad the conversion of land south of U.S. 190 to agriculture.
Every spring the Atchafalaya inundated the forests for a few days to a few months, bringing in fish and crawfish and invertebrates. Decaying vegetation hosted bacteria, food for crawfish and invertebrates. Nutrients released from the decaying process nourished microscopic floating plants, more food for invertebrates. Water-loving mammals followed, feeding on fish. Floodwaters washed them all–fish, bacteria, invertebrates, and tiny plants–throughout the floodway.
Upper Flat Lake supports cypress trees, standing as individuals and in groups, and the stumps of cypress logged early in the twentieth century. Sandy islands support willows. Swampy islands, colonized by cypress and swamp privet, dot the landscape. When the water falls, campers can pitch their tents on them. When the lake floods, dry land disappears. Waterhyacinth float everywhere. The exotic plant, that has proliferated across the south, is a two edged sword in southern waterways. On one hand, it is capable of removing excess nutrients and filtering heavy metals and toxins from polluted water. On the other, it spreads rapidly, clogs the lakes and bayous, and kills the trees it surrounds.[ii]
[i] U.S. Army Corps of Engineers, “Ducks Unlimited,” Around the Corps, July 2002, http://www.hq.usace.army.mil/cepa/pubs/jul02/story23.htm; Louisiana Travel, “Bayou Birds, the Atchafalaya loop, South Farm Unit, Sherburne Complex WMA,” http://www.louisianatravel.com/explorela/outdoors/birding/loops/atchafalayaloop.pdf
[ii] Mississippi River Commission, Atchafalaya Basin Floodway System, Louisiana, Feasibility Study, Main Report and Final Environment Impact Statement, Vicksburg: Mississippi River Commission, 1982, EIS-73, EIS-75-76; Niering, William, Wetlands, The Audubon Society Nature Guides, New York: Alfred A. Knopf, Inc., 1985, 464.