County conservation awarded a $3.4M contract to reduce the height of the dam and revitalize the area for recreation

Changes planned for Linn County’s Pinicon Ridge Park dam aim to turn it into a place where people and aquatic wildlife can live and play safer.

Last month, the county conservation board awarded a $3.4 million contract to Boomerang Construction of Anamosa to modify the roller dam and lower it, allowing for the new recreation opportunities.

The project is expected to begin after Oct. 15. Construction work will continue through 2023 as low water flow on the Wapsipinicon River allows.

The original dam was built by John Peet in 1856 on the Wapsipinicon River downstream from Pinicon Ridge Park, just east of Highway 13. In 1960, Linn County purchased the 182 acres that would become Pinicon Ridge Park and the new dam was completed in 1967.

There’s been a push to modify low-head dams in Iowa — like the one near Central City — to not only improve water quality of rivers and streams, but to improve safety, increase the environmental health and population of aquatic life and to provide better access for paddle sports. Discussion about the future of the Pinicon Ridge Park dam goes back to at least 2017.

“It will really open up opportunities for Central City and park users,” Conservation Deputy Director Daniel Gibbins said. “There will also be accessible walkways and platforms for fishing which will add really good habitats for anglers. It will be a beautiful design and people will just want to be down there to enjoy it.”

But recreation is not the project’s sole purpose. Gibbins said that the design and engineering is rather complex. Plan incorporate a dual passage to balance the river ecology and the safety of paddlers.

The existing dam will not be removed, but will instead be lowered 12 to 18 inches. Boulders and other engineered materials will be placed downstream to allow fish and paddler passage.

The “swirling water” effect of the roller dam, which can trap debris and endanger anyone caught in it, will be eliminated. Fish and mussel passage through a “fish ladder” on the west side of the river will eliminate the current ecological block and promote healthier populations of these species north of the dam, Gibbins said. Splash pools on the east side of the river will allow for safe paddling.

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The river is home to more than 800 aquatic species including the endangered Higgins eye pearlymussel. Native to the United States, the mussel’s habitats in Midwestern rivers have been altered over the years by dams and locks, which have negatively impacted the animal’s ability to travel. Combine that with overfishing, and the mussel has landed on the federal endangered list.

“Safety is a big concern, but the dam is currently also an ecological block to the Wapsi,” Gibbins said. “We don't get fish species traveling upriver when it's low water. They have a really hard time. And the mussel rides on the gills of fish. So it’s important to provide them that ladder to get upstream.

“This will ensure that fish can still travel upstream even in extremely low flow,” he added. “It's designed to keep that open for fish passage. Even at the point paddlesports would be offline due to low flow, the fish could still get through.”

The project is funded through Iowa Department of Natural Resources’ low-head dam/fish habitat program, U.S. Fish and Wildlife, and Linn County Water and Land Legacy Bonds.

The county water and land legacy bonds will cover $1.5 million of the cost and local-option sales tax revenue will cover another $350,000. Grants from the Iowa DNR will pay for $100,000 and U.S. Fish and Wildlife will provide $490,000.

Comments: (319) 398-8255; gage.miskimen@thegazette.com

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