LORIDA, Fla. -- Turkey vultures circled overhead as Lou Toth pointed his boat up the Kissimmee River, or C-38 as it has been known since the Army Corps of Engineers turned it into a poker-straight canal 20 years ago.
"Turkey vultures are not normally found in a wetlands ecosystem," he said. "This river might not look so bad, but biologically it is very degraded."
Originally the Kissimmee meandered among 43,000 acres of wetlands, said Mr. Toth, a senior environmental scientist with the South Florida Water Management District. It had a flood plain 1 mile to 2 miles wide embracing shrub and forest habitats with many species.
But turning it into a straight channel drained or destroyed most of the wetlands. Moving upriver, he pointed out alien wax myrtles that had displaced the willows that once lined the river banks.
Mr. Toth and the water district are part of an alliance that now hopes to turn C-38 back into the twisting Kissimmee River.
To restore the river to something close to its natural state has been a dream of environmentalists almost since the canal between Lake Kissimmee and Lake Okeechobee was completed in 1971.
Now the state of Florida is behind the restoration, as are the Corps of Engineers and the Sierra Club.
If Congress approves, a 15-year project sponsored by Florida and designed and managed by the Corps of Engineers would restore 29,000 acres of the ecosystem.
It would be the largest restoration in the United States solely for environmental reasons, and it would cost $368 million.
It was the Kissimmee's own tendency to flood that led to its demise. In the 1940s, the growing population of central Florida, including ranchers and farmers who had moved onto newly drained wetlands, demanded protection from floods. Congress authorized the Kissimmee River Flood Control Project in 1954.
Although control measures that would have been less environmentally destructive were considered, for economic reasons the corps decided to dredge the river, turning 103 miles of river into 56 miles of canal.
Protests by environmentalists began almost as soon as the canal was completed. In 1983, Bob Graham, then the governor, began a program to save the Everglades that included the Kissimmee, which through Lake Okeechobee provides much of the water to the Everglades.
A demonstration project in 1984 began to show that restoration was technically feasible.
Heading toward the demonstration project, Mr. Toth stopped at a remnant river bend to show how the ecosystem had been changed.
"The canal acts like a sink," he explained. "It draws water into it no matter what you do."
The bend was choked with vegetation because it received little water from the canal, he said. As a result the wetlands disappeared, and alien plant species tolerant of drier conditions moved in.
Low levels of dissolved oxygen in the water, from the diminished flow, reduced fish populations. Many wading birds, including great blue herons and snowy egrets, disappeared, along with more than 90 percent of the thousands of waterfowl.
A few minutes later, Mr. Toth nosed the boat into one of the three bends in the demonstration project.
Here, steel barriers placed across the canal had diverted water into the bends. The water was relatively free of vegetation, and the sandy bottom was visible. A few willows were growing on the banks.
"We found that restoring the flow of water can lead to restoration of the environmental values," Mr. Toth said. "The species that left did come back."