For a long time, Bob Hansis only dreamed about restoring a floodplain. But eventually, he got the chance to do it, and today he can’t believe how well it turned out.
Recently retired after a 37-year career with the Wisconsin Department of Natural Resources, Bob was a watershed supervisor in southwest Wisconsin in 2006, when he got involved with The Nature Conservancy at Military Ridge Prairie Heritage Area, a 95,000-acre grassland in Dane, Green and Iowa counties.
“I saw that the Conservancy had some degraded bottomland property along the East Branch of the Pecatonica River,” Hansis said, “and I started talking with them about restoring the floodplain.”
Turning Back the Clock
Like many streams in southwest Wisconsin, the East Branch of the Pecatonica has high steep banks of beautiful dark soil that crumbles easily into the water. Farming practices in the area in the last century were different than they are today and resulted in a great deal of erosion that covered the floodplain with soil and created these steep river banks.
When the stream rises, portions of the bank slump into the water, and the sediment washes into the Pecatonica and eventually the Mississippi River. The floodplain, now buried in sediment, is dry land rather than the rich wetland habitat that so many species depend on. Bob’s dream was to find a way to restore a healthy, dynamic floodplain.
Healthy floodplains connected to rivers provide many services. They store floodwaters, help recharge groundwater aquifers and filter sediment and pollutants, cleaning the water for people, fish and other wildlife.
“Instead of removing the trees and then ‘armoring’ the banks with rocks, which is the accepted way to restore stream habitat in the region today, I wanted to see if we could remove the sediment that had built up on the floodplain over the past 150 to 200 years and restore it to a more natural condition,” Hansis explained.
New Approach to Floodplain Restoration
Bob developed a restoration plan that called for removing trees like box elder and black willow from the stream corridor. Bulldozers then removed several feet of sediment to expose the native soil layer. The massive machines artfully recontoured the land to mimic the shallow pools, little ponds and other habitat niches that were once part of the floodplain. Finally, the ground was seeded with diverse native plants to restore the wet prairie and wetlands that originally bordered the river.
Enabling the stream to spill over into its floodplain will allow it to naturally form a channel that accommodates the stream’s flow pattern. The soil removed from the floodplain was provided to local landowners, the county highway department and the restoration contractor for use in other projects.
Using Bob’s plan, the Conservancy worked with him and other DNR staff and with the Wisconsin Waterfowl Association to restore two half-mile stretches of the river in 2006 and 2008.
Scientists from the Wisconsin DNR and University of Wisconsin-Madison established several research projects at the site to monitor the effects of restoration on groundwater flow, vegetation response, amphibians and water chemistry.
“It’s been five years since we started the first project, and we’re seeing some great results,” said Steve Richter, the Conservancy’s conservation director in southwest Wisconsin. “The stream banks withstood severe flooding in 2007 and 2008, and very little sediment was released into the river.”
The ecological response has also been impressive, Jeremiah Yahn, a graduate student in Zoology at UW-Madison has been studying the response of amphibians to the restoration.
“Before the restoration, we could count the number of frogs we heard on one hand, and it’s very unlikely any of them were breeding. Now we can hear hundreds of frogs calling on any given night,” Yahn commented.
Excited About the Science
While Bob is pleased with the results at the site, he is just as excited about the science that’s been done there.
“We’ve generated some good discussion among the scientific community in terms of our restoration approach as well as the way we’ve monitored, documented and shared results,” Bob commented, “and that is gratifying.”
One of those scientists, Eric Booth, a research specialist in Agronomy at UW-Madison today, studied the impacts of restoration on groundwater movement and vegetation change for his PhD. He’s already published his research in three peer-reviewed journals and has submitted a third paper for publication.
In addition to the science buzz, there’s been strong interest from agency and nonprofit staff, students and local citizens.
“There was some initial skepticism among professionals and the public about our non-traditional approach to restoring this floodplain,” Hansis said. “But we’ve given numerous tours in the last five years and, especially now that they can see how it has turned out, the response has been very positive.”
But Bob is not resting on his laurels. Now that he’s retired, he is volunteering at the restoration site to make additional habitat improvements that will benefit fish, frogs and other wildlife. And next spring, he’ll wade in once more and help The Prairie Enthusiasts with a similar floodplain restoration on their land in the next valley over.