-Submitted photo Workers from Richards Construction, of Sac City,use a jackhammer attached to an excavator to break up and remove concrete pieces of a dam owned by Corn Belt Power Cooperative. The co-op is removing the dam, located just downstream of Frank Gotch State Park, with help of a state dam mitigation grant. The dam was built in the 1950s and provided adequate water level for a coal plant’s cooling intakes.

HUMBOLDT — Removal of a dam in the Des Moines River just south of Frank Gotch State Park has begun.

Once used for the Corn Belt Power Cooperative’s Humboldt Generating Station, the concrete dam has remained in place since the plant was dismantled in 2000.

When it’s gone, not only will the river be safer for canoes and kayaks, but fish should have more access to the upper forks of the river, thus improving the fishing at Gotch Park, according to Nate Hoogeveen, river programs coordinator for the Iowa Department of Natural Resources.

“This Corn Belt dam, one of the unique things about it is the entire east fork of the Des Moines River doesn’t have another dam on it, going all the way upstream to its headwaters,” Hoogeveen said. “So we will open up over 800 miles of stream to fish passage through this project.”

The DNR worked with Corn Belt to plan the project, and provided a grant of $125,000 from its low-head dam mitigation and water trails program — about 50 percent of the project, Hoogeveen said.

The dam was built in the 1950s, and used to provide an adequate water level for the cooling water intake used to cool the condensers for the four steam turbines in the coal-fired plant.

“The Humboldt generating station was taken down in 2000,” said Kathy Taylor, Corn Belt Co-op vice president of corporate relations. “At that time taking the dam out of the river wasn’t in the scope of the budget.”

A low-head dam like the one being removed can create a dangerous recirculating current that can trap and drown victims immediately downstream, Taylor said.

The co-op has always posted signs warning of the danger.

Swimmers and people in small watercraft like kayaks, canoes and inner tubes are often unaware of hazards these types of dams present, she said.

“Low-head dams are notorious for being drowning hazards,” said Mike Thatcher, Corn Belt vice president of generation. “In fact, many years ago there were three drowning deaths in the vicinity of the dam. It presented a liability to members.”

The dam is just downstream from where the east and west forks of the Des Moines River converge, Hoogeveen said.

It was a good candidate for the grant program.

“Our program has two main goals. One is to eliminate the hazards at these dams, one way or another. Sometimes we build a rapids instead of a dam, if you need to keep the pool,” Hoogeveen said. “The other primary one is fish passage.”

Opening the river to fish also helps mussels repopulate rivers, he said, because they use fish to move their young.

“Mussel species tend to be under a lot of pressure in Iowa,” Hoogeveen said.

“The Des Moines River up there is  a very rocky, rapid stream. It has a lot of cool things about it,” he added. “I think this will allow a lot more people to access the river in that area. Especially with a state park they can stay at overnight, stage at, and then head on downstream.”

Corn Belt hired Richards Construction, of Sac City, to complete the project. Work began across the river from the plant site, which has better access to the dam. The contractor is using an excavator with a jackhammer attached to break up the dam and then remove concrete pieces. An access road was built in the river to allow equipment to reach the dam, which will be torn out down to the riverbed. As progress is made removing concrete pieces, the access road will also be removed.

Rubble from the dam will be buried at the site.

The project will likely be completed by the end of the year.

Funding in the DNR’s mitigation program varies from year to year, and was set at about $278,000, Hoogeveen said. There have been 15 dams mitigated since the program started in 2008, and there are another 20 to 25 projects coming up.