- Associated Press - Saturday, October 25, 2014

MACY, Neb. (AP) - As the boat throttles down and glides into shallow water off the Missouri River’s main channel, Luke Wallace describes the importance of this area and others like it.

Protected from the river’s channel by a finger of soil and rock, this inlet of calm, shallow water is a prime spot for fish to spawn. Insects, plankton and algae those fish eat thrive in these types of areas. Shore birds, water fowl, deer and other animals congregate there as well, the Sioux City Journal reported (https://bit.ly/1wfPnuS ).

“Backwaters are huge reproductive areas. I’ve heard it described as the grocery for the river,” said Wallace, a biologist in the U.S. Army Corps of Engineers Omaha Division’s planning branch.

During the flood of 2011, the swollen river carried tons of sediment, dumped it into these backwater areas and filled them. Sediment deposits cut off slower side channels from the main river. It left fish, such as the endangered pallid sturgeon, without the habitat needed for survival.

Through dredging, the corps is restoring those backwaters and side channels and reviving that habitat. Wallace said wildlife and vegetation are returning to these areas, which didn’t have the visibility of flood-damaged structures such as levees and revetments.

“Only people who regularly use these areas or are on the river would have known these areas were damaged,” Wallace said.

In September, work began on a backwater called Hole-in-the-Rock, located on the Nebraska side of the river near Macy. Contractors will remove 45,000 cubic yards of sediment from the 9-acre site to deepen the pool for the more than 60 species of fish that use it.

Later this month, work will begin to restore a side channel at Middle Decatur Bend near Decatur, Nebraska. Workers there will remove 88,000 cubic yards of sediment. Because of riverbed degradation caused by the flood, water no longer enters the side channel, so the inlet’s entrance will be lowered 2 feet to allow water to once again flow through the area, providing habitat used by catfish, sturgeon and other fish.

The two projects, set to be finished in June, are part of a $972,000 contract.

Project manager Colleen Horihan said the corps has spent between $14 million and $16 million since 2012 to repair 17 flood-damaged shallow water habitat areas between Sioux City and the Iowa-Missouri border. The corps expects to spend $3 million to $5 million more on similar projects in the future.

“All of the shallow water habitats from Sioux City to the Missouri state line were affected to some extent,” Horihan said.

Those projects will help ensure the river’s ecological diversity, said Dave Swanson, director of the Missouri River Institute at the University of South Dakota.

“I think in general, the importance of backwaters has been under-emphasized,” Swanson said. “They’re important as nurseries for fish, important for insects. They really need these areas to do what they do.”

As the boat pulls into Hole-in-the-Rock, Wallace points out the dredge that is digging sediment from the bottom of this backwater area and will eventually leave it 10-12 feet deep, twice its current depth. The water once again will be deep enough for fish to survive in during the winter.

Dredged silt is discharged into the river channel. Wallace said the heavy silt will stay in the river bed while the lighter sand will be carried away rather than be deposited in shallow areas downstream.

Hole-in-the-Rock is smaller than many of the previous projects - one soon to be finished at Glover’s Bend a few miles upriver covers 55 acres and entails the removal of 660,000 cubic yards of sediment - and didn’t have near the sediment as others, Wallace said. But it’s important all the same.

Most of these sites are public areas, popular for hunting and fishing. It’s also the corps’ duty under federal law to maintain habitat along the river, Horihan said.

“If the corps does not repair shallow water habitat, there is a risk of determination of noncompliance with the Endangered Species Act,” she said.

The reason behind the work goes beyond simply meeting legal requirements, Horihan said. These areas are important to the fish, birds and small mammals that depend on them for survival.

“Life safety is paramount to the corps,” Horihan said.


Information from: Sioux City Journal, https://www.siouxcityjournal.com

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