As silt threatens Coralville Lake, nonprofit explores solutions

NORTH LIBERTY -- When Jon Kounkel and his family were deciding where to move in the Midwest, one of the requirements was to be near somewhere with a lake.

Kounkel, who grew up in Spirit Lake near Okoboji and the Iowa Great Lakes, always has enjoyed boating and being by the water. Almost two decades ago, he returned to Iowa with his family and bought a house near Coralville Lake.

“We moved here in the wintertime,” Kounkel said. “The lake was beautiful when it was frozen over and covered in snow. We bought a house on the lake and were really excited to have a place here and be able to enjoy the lake.”

Once winter was over, Kounkel and his family went out on Coralville Lake, which is near North Liberty, for the first time. His daughter pointed out the “chocolate bubbles” in the water.

“We've noticed the lake decline over the 17 years that we’ve lived here,” Kounkel said. “We’ve noticed it continue to silt in and get dirtier and more dangerous.”

Kounkel was passionate about addressing what was happening to the lake and joined the Friends of Coralville Lake, a nonprofit that formed in 2016 and focused on the well-being of the lake. Kounkel currently is president of the group.

The nonprofit, a partner with the Army Corps of Engineers, is developing a multi-year action plan to raise awareness and explore solutions of the increased sedimentation in the lake.

The concern, Kounkel said, is “the lake as it exists today likely won’t in the very near future.” Estimates from the Army Corps say there are 20 to 30 years left before the lake silts in and becomes unusable for boating and other types of recreation.

What’s happening to the lake?

Through the Flood Control Act of 1938, the Army Corps was authorized to build several dams on tributary rivers, including the Iowa River, according to the Corps’ website.

Construction of the Coralville Lake dam began in 1949 but got delayed by the Korean War. The dam was completed in 1958.

The intent of the Coralville Lake dam is to slow down high-water events, said Jonathan Wuebker, assistant operations manager for the Army Corps. There are different missions for which the Army Corps gets funding and for which it is authorized to regulate water, with flood risk management at the top of the list.

But the Army Corps is not authorized for and does not receive funding to adjust water levels specifically for recreation, such as boating and kayaking, Wuebker added.

Over the years, sediment has gathered at the bottom of the lake. The lake’s volume was 492,000 acre-feet when it was built in 1958. By 2000, the volume was down to 421,000 acre-feet.

The rate of siltation has been consistent, currently silting at a rate of 1,300 acre-feet a year, Kounkel said. To put that into perspective, Kounkel said, the volume of increased sediment per year is equivalent to the volume of two Empire State Buildings.

There are no concerns about the integrity of the dam, Kounkel said. Wuebker added how the Coralville dam will be able to fulfill its mission of flood risk management for many years to come, even if the lake eventually silts in.

Exploring potential solutions

Kounkel said while there is “no quick fix,” there are potential solutions.

The first one the nonprofit is looking at is setting up a watershed management authority — an organization that would work to reduce sedimentation flow into the lake.

“You'll never completely stop (the sedimentation), but if we can reduce it so it's one Empire State Building worth instead of two, then that would start to extend the life of lake,” Kounkel said.

Other possibilities include buffer strips and silt traps to slow down or catch the silt, said Derrick Parker, Friends of Coralville Lake founder and current treasurer.

Dredging is costly and dangerous for the environment, Wuebker said.

“To dredge out an area like our marina here at Coralville Lake, $5 (million) to $10 million would be expected, to be completely silted in within two to three years,” Wuebker said. “Do we want to spend $10 million for two years?

“Or do you want to fix the sedimentation problem from where it's originally coming from — the tile systems, the storm sewer systems that are direct drains? Those are all probably better places to start.”

This issue is not unique to the Coralville Lake, Kounkel said. It is something that impacts reservoirs across the country to various degrees, depending on the topography and land use around it.

Lake Geode in southeast Iowa was drained in 2017 in an effort to lower the lake’s bacteria, sediment and phosphorus. The lake was filled back up earlier this year.

The Friends of Coralville Lake contracted a few student groups over the past two years to help study what is happening at other lakes in the Midwest.

“I think there are a lot of lakes in Iowa, or just in the Midwest in general, that are facing the same issues,” Kounkel said. "Other than just silting in, the water quality is somewhat of a concern here at Coralville Lake, too.“

The lake was on the state’s Department of Natural Resources list of impaired waters in 2020 for E. coli bacteria and turbidity, which is how cloudy the water is.

Nonprofit’s campaign to restore the lake

The Friends of Coralville Lake is in the first phase of a multi-year plan that will explore possible solutions and cost. The group also is working to raise awareness and ultimately launch a lake restoration plan if there is interest from the community.

The nonprofit’s overall mission is to enhance Coralville Lake and surrounding land by bringing together organizations, business and individuals. The group helps with trail restoration, cleanups and hosting events, among other projects.

A feasibility study will be one of the first steps of the Save the Lake campaign. The study will gauge interest from community members, local governments and others, as well as scope out potential funding sources.

While the nonprofit is passionate about figuring out solutions, Parker noted that some residents might want the lake to fill in. As the lake fills in, it would become more shallow and more like a swamp, which would be good for duck hunting, Parker said.

“We want to make sure that it is something that the community believes in and would want to support,” Kounkel said of the campaign.

Wuebker encouraged individuals to have an open mind. The bottom line, he said, should be how to best preserve environmental resources.

Kounkel said a tentative timeline is launching the feasibility study in 2022, with fundraising starting in 2023 or 2024 if the community indicates support. A lake restoration plan would begin around the same time as the fundraising campaign, Kounkel added.

Coralville Lake adds more than $76 million to the local economy and nearly 600 jobs. It is the most visited lake in Eastern Iowa, with more than 400,000 household trips per year, according to the Friends of Coralville Lake.

Another reason why people should care, Parker said, is that if nothing is done future generations won’t be able to enjoy the lake in the same way.

“If you want your kids to enjoy the lake the way that we do, get involved,” Parker said.

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