Latest / The Illinois Nutrient Loss Reduction Podcast / Episode 78 | 35 Years of USDA Wetland Restoration
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- **Episode 78 | 35 Years of USDA Wetland Restoration** Marin Skidmore, Agriculutural Economist - University Illinois ACES Source Article - https://farmdocdaily.illinois.edu/2025/11/natures-kidneys-a-review-of-35-years-of-usda-wetland-restoration.html Todd Gleason: This is the Illinois Nutrient Loss Reduction Podcast episode 78. 35 years of USDA wetland restoration. I'm University of Illinois Extension's Todd Gleason. If farmers across the Corn Belt are constantly looking for ways to keep nutrients in the field and out of the water, a new study from the University of Illinois confirms one long-standing USDA program is punching well above its weight. Agricultural economist Marin Skidmore reviewed 35 years of data on wetland restorations. She tells us these so-called nature's kidneys are doing a massive amount of work cleaning up local watersheds, and that could mean big savings for rural water systems downstream. Marin, thank you for joining us, you've written an article for the farmdoc daily website that's titled Nature's Kidneys a review of 35 years of USDA wetland restoration, why were you interested in the topic? Marin Skidmore: There has been previous research studying the benefits of wetland restoration for nearby farmland, looking at benefits for surrounding fields in terms of yield and reducing the number of prevent plant dates. And so there's evidence that these easements can be privately beneficial from the single farmer's perspective. But another major part of the motivation for wetland restoration is this broader environmental benefits that wetlands can help improve water quality at a larger scale. And despite the fact that this program has, the Wetland Reserve Program has existed for 35 years, no one had actually put it to data and tested the benefits of these wetlands that were restored by the USDA. Todd Gleason: So you were looking to try to figure out how much the wetland was helping to reduce nutrient loads in watersheds particularly and sub-watersheds. This seems like it would be very difficult given the comparisons that have to be made. What kinds of things did you do to control what this data managed to show and to make sure that it was finding the items you were looking for? Marin Skidmore: Absolutely. As you said, there are so many factors that can influence the nitrogen and phosphorus concentration in a stream or river on any given day in any given watershed. And so our approach was to compare sub-watersheds before and after a wetland was restored, so we're getting that comparison of the same sub-watershed before and after the first restoration. And then also looking at a really large geographical region. We have the entire Mississippi River basin, and that means that we have different sub-watersheds getting their first restoration and then getting subsequent restorations at different moments in time. So that's the intuition on the specific side, we're controlling for seasonal variation in water quality, you know largely we have higher nutrient concentrations in the spring as we get rainfall and snow melting, variations across space so what is the type of soil in that sub-watershed, what are the slopes surrounding the streams in that sub-watershed, we do directly control for precipitation and temperature in any given month, and through that we really try to isolate the impacts of the wetlands. Todd Gleason: So to be clear, these are USDA programs, they are part of the Wetland Reserve Program or WRP that was folded into the Conservation Easement Program in 2014. In your paper you say the average payment a farmer has to give up these areas completely, though they retain ownership but they cannot farm them, on average they've been paid about $2,700 an acre and then I think that I've got this right that it cost about $650 an acre to be converted into a wetland. The average size is about 100 acres or the median size I should say is about 100 acres. How good are these actually at reducing nutrient loads like nitrogen? Marin Skidmore: They're really enormously successful relative to their size at reducing nitrogen in the surface water. So our estimate of the first wetland easement in the subwatershed is that we find a 62% decrease in ammonia in the nearby subwatershed and 37% decrease in total kjeldahl nitrogen. Those are two different chemical forms that nitrogen can take. Of course nitrogen moves through the nitrogen cycle and different conservation staff members might take a different type of water sample. So we have different ways to measure nitrogen, but in either case we're finding really meaningful decreases from even just this 100 acre restoration. Todd Gleason: Now across the corn belt, most states have been working through a nutrient loss reduction strategy program trying to control the runoff of these kinds of nutrients. You through this research suggest that putting a wetland in is a really good way to do this. Marin Skidmore: We did. Of course we see wetlands as part of a broader approach to reduce nutrient loss. They fit really well into an environment with lots of different best management practices, but our research really suggests that wetlands are a tested and proven method to reduce nitrogen concentrations in the Mississippi River Basin writ large but especially in places like the corn belt that are dealing with perennially high nitrogen concentrations. Todd Gleason: And you also took some time near the end of this article which again people can find on the farmdoc daily website, search for Nature's Kidneys and it should come up, you suggest that for communities that have surface water this is a really good way upstream to make sure that they have cleaner water coming into the system and I think more cost efficient? Marin Skidmore: That's exactly right. Local utilities, specifically public water systems are already required to maintain nitrate levels in the water they supply for drinking water below a level set by the Safe Drinking Water Act. For utilities that have high nitrogen or nitrate levels in their source water, this can be a meaningful cost and especially for small communities that have difficulties with their local budgets, anything that helps reduce the water treatment costs can really have an impact. And so directly lowering nitrogen in the source water reduces those water treatment costs and helps pay back the cost of the initial wetland restoration. Todd Gleason: And importantly, in this particular article, you took time to make note that the producers, farmers, the landowners that you talked to had anecdotally really good feelings about putting these wetlands in and what this restoration meant not only to their community but to their families I believe. Marin Skidmore: Yes, I think one thing to understand about wetland restoration is that many times wetlands are being restored on what continues to be a working farm. This is still in the hands of a family that is engaging in agriculture, but now in addition to their working profitable farm, they have a small area that can be shared with their children, with future generations where they can as you said anecdotally go fishing, go for hikes, have picnics by the stream. Of course the wetland itself is quite swampy, but it's this legacy that you can share with your family and because of the nature of these permanent easements it's something you know is going to be shared with the next generation. Todd Gleason: We've been talking with Marin Skidmore today, she is an agricultural economist at the University of Illinois and co-authored an article called Nature's Kidneys, it's a review of 35 years of USDA wetland restoration Marin thank you for taking so much time for me today. I appreciate it. Marin Skidmore: Thank you Todd. Todd Gleason: Marin Skidmore is an agricultural economist on the Urbana Champaign campus of the University of Illinois, you may read her Nature's Kidneys article on the farmdoc daily website. Thank you for joining us for this edition of the Illinois Nutrient Loss Reduction Podcast on behalf of our extension educator team including Rachel Curry, Nicole Haverback, and Luke Zwilling, I'm Todd Gleason.