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$11.9 million Mississippi River island project adding habitat for fowl, fish

This map shows the locations of islands to be created in the lower part of Pool 9 of the Mississippi River. It also shows the locations of deeper holes created by backwater dredging. U.S. Fish and Wildlife Service map

Construction has resumed on an $11.9 million project to improve fish and wildlife habit on Pool 9 of the Mississippi River.

“This will be great for fish, waterfowl, shorebirds and the people who enjoy them,” said Karen Osterkamp, a fisheries biologist with the Iowa Department of Natural Resources.

The Army Corps of Engineers is constructing seven islands and three emergent wetlands within the 2,200-acre Harpers Slough backwater between river miles 650 and 653 at lower end of the pool.

The islands — built with dredge spoils from the main channel and the slough — will be revegetated and armored with rock to prevent erosion.

The nearly 100 acres of new islands will limit wave action, reducing turbidity and enhancing the growth of aquatic vegetation, according to Wendy Woyczik, deputy manager of the McGregor District of the Upper Mississippi River National Wildlife and Fish Refuge.

“We’re hoping to grow more wild celery, which is a favorite of the canvasback ducks,” she said.

The backwater dredging will create deeper holes for overwintering fish habitat. Woyczik said.

“One of the main goals is to maintain habitat for the tundra swans and canvasback ducks that stop on pool 9 during their migrations,” said Mike Griffin, the Iowa DNR’s Mississippi River wildlife biologist.

Though funded through the Corps’ Upper Mississippi River Restoration — Environmental Management Program, the project was planned and designed cooperatively with the U.S. Fish and Wildlife Service, U.S. Geological Survey and the natural resource departments of both Iowa and Wisconsin.

Griffin said he expects the emergent wetlands to bear large crops of arrowhead plants, whose underwater tubers, known as duck potatoes, are a preferred food of the thousands of tundra swans that visit the pool each year.

Since the creation of Lock and Dam No. 9 in 1937, many of the natural islands in the lower pool and the flood plain forests they support have eroded and disappeared, reducing habitat available for migratory birds.

Griffin said the number of tundra swans and canvasbacks visiting Pool 9 has remained stable, and the project is intended to ensure that continues.

“Pool 9 is a critical stop for migrating waterfowl, and it’s important to maintain that function,” said Lansing ornithologist Ric Zarwell.

The rock-armored islands will provide excellent habitat for smallmouth bass, and the dredged areas — typically at least 8 feet deep with little current — will provide suitable overwintering areas for bass and panfish, Osterkamp said.

Three of the largest dredge cuts, clustered close to the Iowa shore in the Wexford area, should be especially popular with ice anglers, she said.

Construction is scheduled to be completed in 2018.

l Comments: (319) 934-3172; orlan.love@thegazette.com