Riverine Wildlife Habitat Created as Part of Bridge Construction

James Ed. Ducey

A project to replace the historic Meridian Bridge included dirt excavation that restored a riverine chute along the Missouri River channel.

Sediment was excavated from the river side channel to provide the fill dirt needed to construct a new approach to the Nebraska side of the bridge for Highway 81, south of Yankton. The bridge replacement project is being carried out by the Nebraska Department of Roads (NDOR).

"Construction of a bridge could potentially have negative effects on surrounding fish and wildlife habitat, but in this instance, it will actually improve habitat," said Robert Harms, a biologist with the Fish and Wildlife Service ecological services office in Grand Island.

About 10 acres of backwater area were restored, with work mostly finished this autumn.

The new backwater will improve habitat for the "federally endangered pallid sturgeon, Least Tern, scaleshell mussel, and for other fish and wildlife, including the sturgeon chub and false map turtle," according to a FWS press release. The tern and sturgeon will benefit from "small fish and insects that are often abundant in backwater areas, and provide a food resource."

Migratory birds that will benefit include waterfowl and wading birds, said Harms, mentioning the Belted Kingfisher, Great Blue Heron, as well as other water birds, such as the American Coot or Pied-billed Grebe. "The habitat will provide resting habitat for ducks and geese as they migrate in the spring and autumn. Much of this type of habitat has been lost over the years on the Missouri River," Harms said, "resulting in a drastic decline in the abundance and diversity of native fish and wildlife species."

Once construction of the piers for the new bridge is completed, an outlet will be excavated to connect the backwater area to the Missouri River channel.

The backwater area - along the Missouri National Recreational River - will be owned by the National Park Service, which is supportive of adding water flows through the site to create a flowing side channel chute, said Harms. Discussions to undertake this conversion should occur in the next couple of years.

The NPS also plans on building a trail system through the site, south of the chute, according to the NDOR project website..

During construction, the NDOR is taking measures to avoid any impact to endangered or threatened species. Specific items, according to a news release, include:

• "Restrictions on the placement of material into the river and prohibition of pile driving or demolition activities during the critical spawning time for pallid sturgeon in the late spring and early summer;
• "Reducing the length of the temporary causeway to avoid changes in hydrology that could impact spawning habitat and stationing of two spill kits at the construction site to contain accidental spills from equipment should they occur;
• "Construction equipment, such as barges and tow boats, brought in from offsite locations were carefully inspected for zebra mussels, and invasive species that could severely impact the ecology of the river."

Surveys for the presence of the Least Tern, Piping Plover, scaleshell mussel and wintering Bald Eagle were also carried out to ensure bridge construction would not disturb these species.

NDOR "considers the backwater restoration project a win-win addition to the project," said Scott Brummond, a district environmental compliance officer with the agency. It was "a win for many fish and wildlife species and the environment and a win for the taxpayer and contractor due to the available fill material from this adjacent area being used in the embankment for the bridge approach."

This project was a collaborative effort among several agencies to develop an "environmentally friendly construction plan," according to the news release.

The Nebraska Department of Roads worked with the South Dakota Department of Transportation, U.S. Fish and Wildlife Service, National Park Service, Nebraska Game and Parks Commission, South Dakota Game, Fish and Parks Department, and the Federal Highway Administration.

The Meridian Bridge was built in the 1920s, and the new bridge is providing a replacement.

NDOR Yankton Bridge project website