Are Minnesota Creek Restorations Working?

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Minnesota taxpayers and fishermen have spent millions of dollars realigning dozens of streams and streams across the state to stop erosion, clean up the water, and bring back trout and other aquatic life.

Now is the time to find out how well these projects actually worked.

A team of researchers from Duluth will assess several trout streams that have undergone extensive restoration work over the past decade. They intend to find out whether these projects have not only brought back the trout and water bugs they eat, but also whether the realignment has achieved more ambitious goals, such as slowing erosion and resisting heavy rains. and flooding.

Perhaps more importantly, the state needs to know whether the realignment of the streams disrupted their natural connection to groundwater or unintentionally made some problems worse, said Valerie Brady, aquatic ecologist at the Institute for Research on University of Minnesota Duluth Natural Resources.

“When you do these big earthmoving type projects, you’re lucky that it can really mess up the connectivity of this stream with the groundwater,” Brady said. “We haven’t been able to measure this before. So now that these places have had a few years to recover, we can see if things have improved or if they have accidentally made something worse.”

Erosion, the root problem in major restorations, isn’t going away anytime soon. Other waterways will realign in the years to come as they continue to wash away land near homes, roads, bridges and businesses.

The appearance of clear, swift, and scenic streams in the woods of northeastern Minnesota may belive their sometimes tenuous conditions. Most of the state is made up of sandy or limestone soils, which can quickly absorb precipitation, even during heavy storms. But northeast Minnesota is made up of clay that has likely been hardened for eons under an ancient lake, Brady said.

“It’s just bedrock and clay, and the streams rise quickly when it rains,” Brady said.

When Minnesota was settled, the stormwater problem worsened. Trees were cut and farms, roads and houses were built. Ditches have been dug to remove water from the development. All of this pushed more water through the system.

“Now we have these little streams that get all kinds of water that the canals can’t handle at this volume and speed,” Brady said. “So these streams are desperately trying to realign their banks and widen their channels, but we won’t let them do that because that would eat away at a road or wash away a bridge.”

Storms have also become more severe and occur more often due to climate change.

Over the past 20 years, the state has solved the problem by realigning dozens of creeks, including Knowlton and Sargent creeks in Duluth and the Stewart and Little Stewart rivers to the north. Streams have been diverted from roads and homes and cut into more natural winding paths, which can slow water flows. Their shores were also buffered by gentler slopes that didn’t erode as quickly.

But Minnesota’s waterways have always been closely linked to its groundwater. Much of the life in streams depends on that clean, cold groundwater that gushes out. It’s possible that realigning the streams could sever their connection to groundwater, leaving them warmer, murkier and more lifeless, Brady said.

Now is a great time to assess the restorations, most of which took place with money raised through the Legacy Amendment that voters approved in 2008, said Doug Dieterman, a DNR researcher.

About 80 restoration projects, using a variety of engineering techniques and habitat designs, have been completed over the past 20 years in Southeast Minnesota alone, he said. Many more will be done before the Legacy Amendment ends in 2034. Enough time has passed to get a clear idea of ​​which types of projects are holding up and which are not.

“The big question is why we could not stick it out,” Dieterman said.

The work of researchers in northern Minnesota will be funded by the state’s Environmental and Natural Resources Trust Fund and will last approximately four years. The group will focus on up to seven streams near Duluth and the Arrowhead area, but have yet to select them. Finding streams that have intact expanses is important to get a clear idea of ​​how much groundwater should flow into the realigned leg, Brady said.

She said she expects the results to be complex, but revealing.

“This will give us a deep insight that these systems didn’t have in Minnesota,” she said. “The big question is whether we can help find ways to do it better if there is a problem.”

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