Rapids replacing Turkey River dam

A low head dam on the Turkey River south of Cresco is being transformed into a 350-foot long stretch of rapids.

The conversion of Howard County's Vernon Springs dam is the first major dam mitigation project to be constructed since the Iowa Legislature appropriated funds to initiate the low-head dam public hazard program.

Jeff Korsmo, a park ranger with the Howard County Conservation Department, said the project will cost between $250,000 and $300,000 and will be paid for with grants from the Iowa Department of Natural Resources, the U.S. Fish and Wildlife Service and the National Fish and Wildlife Foundation.

Korsmo said the project is intended to stabilize a flood-damaged dam, connect upstream and downstream portions of the Turkey River fishery, reduce safety hazards associated with the circulating currents of low head dams and improve recreational opportunities.

“We expect this project to benefit all fish species, both in the river and the” impoundment above the dam, DNR district fish management biologist Bill Kalishek said.

Korsmo said the dam was built in the 1850s and was in a “dilapidated condition.” Flooding in 2008 washed out an 80-foot section of the dam cap, which underscored the need to upgrade the structure, he said.

The mill pond above the dam is heavily used by anglers and other boaters, so the Conservation Department settled on the arch rock rapids, which will maintain the upstream pool depth while securing other safety, recreational and environmental benefits, he said.

“Something has to be done to address the issue of obsolete and unsafe dams, and the arch rock rapids seems to be the wave of the future,” Korsmo said.

Other scheduled structural mitigation projects include a dam removal on the Yellow River in Allamakee County, rapids conversions on the Big Sioux River in rural Lyon County and the Skunk River in Ames and conversion of a dam to a whitewater course on the Cedar River in Charles City.