SIOUX CITY -- An environmental plan developed in part by the U.S. Army Corps of Engineers calls for building and refurbishing hundreds of acres of Missouri River habitat in order to help the endangered pallid sturgeon and two bird species survive.

The corps' preferred alternative contained in the Final Environmental Impact Statement for the Missouri River Recovery Plan does not include artificial spring or fall rises in river levels, but it does include a possible one-time surge in reservoir releases to see if the sturgeon will use it as a spawning cue.

The document, consisting of hundreds of pages and released in late August, concludes more than five years of study. It aims to aid recovery of the pallid sturgeon, least tern and piping plover for the next 15 years and comply with the federal Endangered Species Act. Both the sturgeon and tern are listed as endangered, the plover as threatened.

Public comments will be accepted through Oct. 22. After reviewing those comments, the corps could issue a Record of Decision as early as November and begin implementation.

"It's been a monumental task. It feels pretty good to be at this point in the process so we can move ahead," said Mark Harberg, program manager for the  Missouri River Recovery Program.

The plan does not replace the Master Water Control Manual, which guides the corps' operation of the system of dams and reservoirs to balance the needs of the Missouri River system's authorized purposes of flood control, hydropower, recreation, irrigation, navigation, water supply, environmental preservation and water quality control.

The final EIS, developed by the corps in cooperation with the U.S. Fish and Wildlife Service, comes after nearly two years of review and revisions of a draft plan issued in late 2016. In that draft, the corps favored the third of six alternatives. That opinion has remained the same after receiving more than 450 comments from the public and additional input from scientists and government agencies.

"The result of that was generally the same conclusion," Harberg said. "They helped us identify that as probably the best alternative."

The plan calls for:

-- Sturgeon spawning habitat construction: The corps would build spawning reefs of rock and gravel at sites from Gavins Point Dam near Yankton, South Dakota, to the Omaha area. The corps would monitor their effectiveness in encouraging sturgeon spawning before deciding whether to build more. The sturgeon continues to struggle to spawn and reproduce naturally in the river. Hundreds are reared in hatcheries and released each year into the river.

-- Early life stage habitat: At total of 12 habitat areas would be built below Kansas City, Missouri. The proposal includes modification of existing wing dikes or construction of new ones to intercept sturgeon larva, which drift after hatching and can be carried away by the swift river current, and steer them into slower, shallower water where young sturgeon can feed and survive before moving into the main channel. Some 750 acres of new habitat and modification of 1,500 acres of existing chutes and backwater areas are included in the plan.

-- Spawning cue test: Scientists would monitor sturgeon movements based on the natural rise and fall of the river from tributaries downstream of Sioux City. After eight years, they would decide whether to test a spring release to raise the river level and see if it causes the fish to spawn.

-- Sandbar construction: The corps would create an average of 332 acres of sandbars per year in three stretches of the river -- Gavins Point Dam to Ponca, Nebraska, and in two reaches farther upriver in the Dakotas. In many cases, sand from the river bottom near existing sandbars would be dredged to build up sandbars so they stay above water during the plover and tern nesting seasons. Both birds nest on the sandy structures.

Other alternatives included doing nothing and a variety of manipulations of river flow to naturally create sandbars and encourage spawning.

David Swanson, a University of South Dakota biology professor and director of USD's Missouri River Institute, said the preferred alternative doesn't preserve the river's biological diversity as much as one of the other alternatives. He favors the development of more habitat for the sturgeon, plovers and terns, but he understands that the corps must compromise environmental concerns with the river's other authorized purposes.

In that sense, the preferred option probably offers the best balance, Swanson said.

"I think it capitalizes on some of the things they're already doing," he said. "For myself, I think I'm probably OK with it. I don't think it's probably going to result in much change for numbers (of endangered species). I think it maintains the status quo."

The corps' preferred alternative is probably the best of the six, "but it's lacking in several ways," said Donald "Skip" Meisner, of Sioux City, a member of the Missouri River Recovery Implementation Committee, or MRRIC, which represents local, state, tribal and federal interests throughout the Missouri River basin.

Meisner said he and other committee members appreciate that the plan does not call for artificial flow increases in the spring or fall, allowing for more stable flows for recreation, navigation and downstream water intakes and better controlling bank and riverbed degradation.

Some committee members believe there are more efficient ways to build bird habitat rather than sandbars that will eventually wash away in the river channel. Meisner said he and others prefer off-channel habitat creation and establishment of habitat that's near the river rather than in it.

Finally, Meisner wondered how the corps will pay for what's included in the preferred alternative, or any of the alternatives, for that matter.

"The costs for all of them are way above what Congress is appropriating," Meisner said.

Actions included in the preferred alternative would cost an estimated $44 million-$45 million annually for 15 years. Costs could reach more than $1.8 billion over 50 years, but estimates that far into the future are not too reliable, said Aaron Quinn, a corps environmental research specialist.

"This cost estimate doesn't lock us in to spending that much," Quinn said.

Costs include habitat construction and refurbishment, land acquisition, channel widening, monitoring, evaluation, research, equipment and staff time.

All corps budgets will ultimately require approval from Congress. Nothing has been finalized, Quinn said, and more detailed budgets will be developed once the corps releases its Record of Decision.

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