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- Nutrient runoff into the Mississippi River is causing freshwater problems — including "dead zones" in the Gulf of Mexico.
- A pilot wetlands project in Illinois is showing that manmade wetlands can reduce such runoff — success the Conservancy hopes can be a model for farms everywhere.
- Animals, birds and native plants are also returning to the wetlands in abundance.
By Julianne Beck
How can wetlands in Illinois help save marine life in the Gulf of Mexico?
Studies now show that manmade wetlands — when strategically placed on farms — can actually help remove excess nutrients from agricultural runoff and "clean" tributary rivers before they enter the Mississippi River and eventually the gulf.
Nature.org recently visited a pilot wetlands project the Conservancy manages on a farm in central Illinois' Mackinaw River Watershed. According to Conservancy aquatic ecologist Maria Lemke, the project could have dramatic impacts on agriculture all along the Mississippi…and beyond. Nature.org sat down with Dr. Lemke to find out more.
Nature.org: What motivated The Nature Conservancy to install wetlands on a corn and soybean farm?
Maria Lemke: First, it's not just any farm. The Franklin Demonstration farm is a 250-acre property located in the Mackinaw River Watershed in central Illinois.
It is a collaborative project where scientists, landowners, farmers, universities and agricultural organizations are coming together to test the ability of new technologies to improve water management in an agricultural setting.
Nature.org: OK, but why the wetlands?
Maria Lemke: Our goal is to reduce the amount of excess nutrients, like nitrogen and phosphorous, in the water leaving the farm before it enters the Mackinaw River.
We learned from previous research in the watershed (conducted with Illinois State University) that cleaning surface-water runoff with common techniques like grassed waterways and stream buffers is not sufficient to reduce nutrient levels, because most of the farmland in the Midwest is drained through underground pipes rather than on the surface.
Instead, we decided to test constructed wetlands, because they collect water coming from the underground drainage pipes and filter excess nutrients out before the water reaches the river. This technique allows us to clean a larger quantity of water and to benefit from the powerful natural filtering ability of a wetland. We installed 13.3 acres of wetlands on the farm in 2006.
Nature.org: You have just released a new set of data from 2008. How are the wetlands working? What do you have planned for spring 2009?
Maria Lemke: Our research attempts to clarify not only the amount of nutrients that can be removed from tile (or underground run-off) using wetlands, but also what size those wetlands need to be in order to have the greatest impact.
We have come closer to finding that answer when we look at the new data from 2008 along with earlier data from 2007. In 2008, our region experienced significant flooding. Under these strained conditions, we found that the wetlands continued to remove large amounts of nutrients before sending the water into the Mackinaw River. As the wetlands became more established in 2008, we saw an increased presence of native vegetation and use by wildlife. Also, in 2009, we will continue to evaluate changes in the run-off and work with our partners to better understand how to manage these wetlands to their highest capacity.
Nature.org: How exactly have the wetlands changed the landscape of the Franklin farm?
Maria Lemke: First, many native wetland plant species are now flourishing in a number of the wetlands — including arrowhead plant, blue lobelia and various species of rushes and sedges.
And as more areas of the farm are returned to a natural state, increasing numbers of wildlife species have been observed taking advantage of the new habitat. In the spring, several birds, including Sora rails were seen inhabiting the constructed wetlands.
Also, Baltimore orioles, indigo buntings, rufous-sided towhees and common yellowthroats are frequently seen in the recently opened areas of the woodlands. Dickcissels and other grassland birds are now common to the prairie nursery area and unmowed grasslands.
Finally, white-tail deer continue to thrive at the farm and large numbers were observed during an aerial survey conducted by the Illinois Department of Natural Resources in February 2008. We also see turkey, fox, coyote, hawks and owls among the wildlife at the farm.
And as the oak/hickory woodlands above the west floodplain wetlands continue to be cleared of brush and other unwanted vegetation, numerous species of forbs and grasses specific to open woodlands and savannas are spreading throughout the area.
Nature.org: Do you think your project will lead to the construction of more wetlands on farms in the Mississippi River Basin?
Maria Lemke: I do hope that as we document the benefits of wetlands, more landowners in the basin will choose to install them on their farms. Illinois properties send an especially high level of nutrients to the Gulf of Mexico — so if we reduce that number on a large scale here, we stand to make a big impact on the gulf.
And in the long run, farmers who practice sustainable agriculture are protecting the resources (such as fresh water) that they need to prosper into the future. Due to an increasing demand for clean water and farm products, it will be critical to expand techniques that protect water without unnecessarily compromising agricultural production.
So as we learn how the wetlands on the demonstration farm are working, we are also busy communicating our results to other researchers in the watershed. We are working with the Illinois State Water Survey to develop hydrologic models for use in key areas in the Mackinaw River watershed.
And wildlife need more wetlands in Illinois and across the Midwest for habitat. In particular, the Mississippi River is a major route for migrating waterfowl in the fall and spring, and the wetlands along the way are a restful and nourishing stop for them.
By measuring what works in various landscapes like the Mackinaw River watershed, we can target the implementation of similar practices in locations where they will be most effective.
Julianne Beck is a media relations manager for The Nature Conservancy.
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Photo credits (top to bottom, left to right): © Tim Lindenbaum/TNC (Constructed wetland at the Franklin Demonstration Farm in the Mackinaw River watershed); © Mark Godfrey/TNC (Maria Lemke)
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