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Restored flood plains can reduce flooding and runoff, save wildlife By SARA SHIPLEY Post-Dispatch 07/27/2003
LISBON BOTTOM, Mo. - Cradled in a rare side channel of the Missouri River, a turtle poked its head through water as rich and brown as homemade broth. A great blue heron stalked its prey in calm pools nearby, and a quail whistled from a forest of young cottonwood trees.
Tom Bell stepped from an aluminum boat onto a rump of land cross-hatched with deer and turkey tracks and wondered if Lewis and Clark floated past something like this on their westward journey 200 years ago.
"This is the best place I know of to see what the river used to look like," said Bell, squinting against the sun. "It's not the same as it used to be, but this is the compromise we have right now."
As manager of the Big Muddy National Wildlife Refuge, Bell has a view of the river's past - and perhaps part of its future.
The U.S. Fish and Wildlife Service has purchased 10,000 flood-ravaged acres along the Missouri River since the Flood of 1993 punched holes in corn and soybean fields at Lisbon Bottom, eventually creating a new chute, or side channel. The agency hopes to expand the refuge to 60,000 acres.
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The $8 million project exemplifies a growing appreciation for flood plains' natural benefits. Undisturbed flood plains act as a nursery for many types of fish, plants and animals. They also filter water pollutants and reduce flood damages by storing and conveying water.
And the Environmental Protection Agency says that flood plains host 80 percent of the nation's remaining wetlands, considered crucial for wildlife habitat and water quality.
More communities around the nation are figuring out ways to save money by restoring flood plains instead of relying solely on dams and levees for flood control. For example, the Charles River Natural Valley Storage Project in Massachusetts avoided construction of a $100 million dam and levee project by setting aside 8,500 acres of flood plain wetlands. The land cost $10 million and stored as much water as a medium-sized reservoir.
Restoring the flood plain makes sense for many reasons, said Rick Hansen, a biologist with the fish and wildlife service's office in Columbia, Mo.
"We think it's good for the river, we think it's good for fish and wildlife, and we think it's good for lowering flood heights in other areas," Hansen said.
Even the Army Corps of Engineers, the nation's biggest levee builder, is warming to the idea of "nonstructural" approaches to flood control. While the agency supports the construction of new or raised levees in places such as Chesterfield, the corps is removing or setting back levees elsewhere under a mandate of ecosystem restoration.
Just downstream of Lisbon Bottom, the corps and the fish and wildlife service together bought about 5,000 acres of Missouri River flood plain called Overton Bottom. Divided by the Interstate 70 bridge, the former farmland is managed on the north side by the fish and wildlife service, and on the south side by the Missouri Department of Conservation.
The corps has dredged a ditch on the north side in hopes of creating an artificial backwater area. But the chute is far from natural, because the corps controls water levels to prevent the river from changing course.
Corps engineer Mike Chapman and an assistant recently shot video images of the bottomland from a high bluff across the river. "We're doing an informational video (for landowners) to show how we're trying to create shallow water habitat," said Chapman, who describes himself as a "green" engineer. "If it floods, the water's going to go somewhere," Chapman said. "If it goes on the Big Muddy, that's less that would go on Joe Farmer."
Farmers have been concerned about such projects in part because flood plain land is such fertile ground for farming. The Missouri Farm Bureau has opposed further expansion of the Big Muddy wildlife refuge and similar public land efforts. Instead, the organization supports options for keeping the land in private hands.
"We think there are other ways to address the issue of flooding rather than purchasing the land and taking it completely out of production," said Leslie Holloway, director of state and local government affairs for the Missouri Farm Bureau.
Most of the Missouri, Mississippi and Illinois flood plains have been cut off from the rivers by levees, leaving modern ecologists and hydrologists few opportunities to study the benefits of a more natural river system.
The Flood of 1993 provided the perfect science experiment. More than 1,000 levees failed, allowing the river to reclaim historic channels carved by ancient glacial flow.
Biologists discovered that, despite the flood's seemingly destructive nature, the high water delivered an ecological bonanza.
The flood, which lasted from spring to early fall, allowed a wide variety of fish species to spawn in the relative protection of slow-moving flood plain water.
Staff members from the Illinois State Natural History Survey collected 52 juvenile fish species on the Mississippi River flood plain near Grafton during the flood, indicating that adults had laid their eggs nearby.
Adult fish populations soared the next year as the baby boom of fish matured. Researchers caught more than twice the number of black crappie per hour in 1994 than they had seen before the flood.
"The flood was actually good, in that it opened up the flood plain to a lot of fish," said aquatic ecologist Richard "Rip" Sparks, who works for the natural history survey.
On the Missouri River, biologists found that the Lisbon Bottom chute attracted twice as many fish species as the open river. Sampling turned up 62 species in the chute, including paddlefish, sickle fin chub, sturgeon chub, freshwater drum, river carp suckers and rare blue suckers.
"The species diversity was incredible," said Joanne Grady, a fishery biologist with the U.S. Fish and Wildlife Service.
Grady was most excited about catching baby pallid sturgeon, a federally endangered, sharklike fish that can live 70 years or more.
"It was the first documentation of pallid sturgeon reproduction on the Missouri River, ever," she said.
Flood plains benefit turtles, birds, plants
Other wildlife also rely on occasional flooding. River ecologist Ken Lubinski says this "flood pulse" triggers life cycle events for many species.
"For turtles, it's when they nest. Herons and great egrets that nest in the tops of flood plain trees come when the river is up and fish in the shallow water for frogs and small fishes," said Lubinski, with the U.S. Geological Survey's Upper Midwest Environmental Services Center in Lacrosse, Wis.
Migratory birds frequently follow flood plains en route from northern nesting spots to southern wintering places. An estimated 60 percent of the nation's waterfowl pass over the confluence of the Mississippi and Missouri rivers, according to the Great Rivers Habitat Alliance.
Beyond fish and wildlife habitat, undisturbed flood plains act as a natural water purification system. Much in the same way that multimillion-dollar wastewater treatment plants filter out contaminants, flood plains harbor green plants and microscopic organisms that use up excess nitrogen and phosphorus.
Fewer flood plains may increase Dead Zone
Many ecologists link the disappearance of natural flood plains and wetlands with the growth of the Dead Zone in the Gulf of Mexico. Excess nitrogen runoff from upstream states feeds the growth of algae, which eventually uses up dissolved oxygen as it dies and decomposes on the ocean floor.
The Dead Zone grew to its biggest area ever last summer - more than 12,000 square miles, greater than the size of Massachusetts. Fish, shrimp and clams can't live in the low-oxygen water.
Lubinski said USGS research has found that the Upper Mississippi River flood plain now recycles only about 2 percent of the nitrogen that flows downstream. If the flood plain were opened to the river, that number could be increased to 15 percent, he said. A much greater benefit would come from restoring the broad flood plains on the lower Mississippi between Cairo, Ill., and New Orleans, he said.
Illinois project may show benefits of flood plains
A massive, private restoration project in Illinois aims to enumerate all the benefits of natural flood plains.
The Nature Conservancy is converting 2,000 acres of former farmland in Spunky Bottoms to an experimental restoration area. The land, on the west side of the Illinois River in Brown County, had produced "extremely marginal" crops for several years because of flooding and water saturation, said Michael Reuter, chief conservation officer for the Illinois chapter of the Nature Conservancy.
The nonprofit conservation group is working with the Corps of Engineers, Illinois and other agencies to open the land to flooding. Since the conservancy bought the first 1,100 acres in 1997, 12 species of endangered or threatened wildlife or plants have returned to the property, Reuter said.
Eventually, the corps plans to build a multimillion-dollar gate to regulate water levels in the bottoms. The idea is to maximize use by native wildlife, like paddlefish, and try to keep out invasive species such as carp, Reuter said.
Lubinski, assigned to the Nature Conservancy for two years, is trying to quantify how such restoration projects might benefit the environment and reduce flood losses. For example, could downstream levees be avoided if more flood plain land were set aside? Could a small town reduce water pollution and save money by using flood plain wetlands to filter wastewater effluent?
He said the goal is finding "win-win situations where we're not only protecting environmental resources," but also protecting economic resources.
Reporter Sara Shipley:
E-mail: sshipley@post-dispatch.com
Phone: 314-340-8215
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