Wetlands are parts of our landscape that are either permanently or seasonally wet. As a consequence, a specific community of plants has adapted to wetland soils that are either inundated or saturated for at least part of the year. Many types of wetlands exist, each with a community of plants adapted to specific conditions that are determined by the hydrology (the source, periodicity, and quality of the water supply), and the underlying soil chemistry. Some wetlands, such as fens or sedge meadows, may be fed by subsurface or surfacing groundwater. Others, such as a floodplain forest, are periodically flooded by overflowing rivers or streams. Still others, such as bogs or vernal pools, capture rainwater in depressions or basins on the land. Marshes are areas with plants that normally grow in relatively shallow water, while a swamp is much like a marsh that is forested.

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Wetlands provide all of us with critical services.  They remove pollutants and toxic substances, reduce flood and storm damages, provide important habitat for wildlife, recharge groundwater supplies, and provide valuable open space and recreational opportunities, such as fishing, hunting and bird watching. The value of wetlands is becoming ever more evident as they continue to be lost.

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Throughout the 19th and much of the 20th centuries, wetlands were regarded as a waste of land – they were good for nothing. In addition, settlers and even many people today have viewed them as a source of mosquitoes, unpleasant odors, and disease. Because abundant wildlife and fresh clean water were in such ‘limitless’ supply, we were unaware of the important role played by wetlands in maintaining the systems on which our survival depends. Nor were we aware of the direct relationship between wetland loss and the intensity and frequency of floods. Consequently, about 80 to 90 percent of the region’s wetlands were drained, ditched, filled or levied off to make room for what we once believed were ‘more important uses’: agricultural, urban, industrial and recreational development. We are only now beginning to understand the heavy price we pay for development in wetlands.

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Before restoration begins, it is critical to develop an overall restoration strategy. This requires some detective work to determine the extent and nature of previous wetlands at the site. This may include a historical investigation of previous land use and hydrologic modifications, a mapping of the extent of hydric (wetland) soils, and a survey for the presence of remnant wetland adapted plants. From the emerging picture of what once existed, the restoration ecologist must decide if or to what extent the previous wetland can be restored. Finally, a plan must be put together for restoring both the hydrology (returning water to the landscape) and reintroducing the wetland plant community. If both of these goals can be met, many elements of the wetland animal community will find their way back all on their own (if you build it, they will come!).  

Restoring hydrology is the process of returning water back to the landscape. Groundwater may have been drained or surface water diverted. For example, most Midwestern farmers installed drain tiles and/or ditches in their fields to carry groundwater or rainwater off the site so that they could grow crops. By disabling or removing these tiles and filling the ditches, water will once again percolate into the ground to recharge pools, ponds and streams. In other areas, levees or dams might have kept water from reaching a site. By removing a dam or “notching” a levee, water can once again flow. This can be a relatively easy process, but it also might require altering the topography with heavy equipment. At times, it may not be possible to completely restore the previous hydrologic conditions because the source of water has been cut off somewhere offsite, or where a full restoration might threaten downstream resources. But once water has been successfully returned, soils will begin to form the ‘hydric’ characteristics that support wetland-adapted plants, which in turn support the many animal species that depend upon them.

Restoring a wetland plant community generally means two things: restore native wetland plants and eliminate or manage invasive species. Each of these two components is part art and part science – their success depends upon close monitoring and quick response, especially in the initial stages of the restoration. Where wetland soils have remained relatively undisturbed, a wetland plant ‘seed bank’ may simply await water’s return to stimulate germination and reestablishment. However, these opportunities are rare, and many species may have to be restored from seeding or the installation of pre-germinated plugs. A combination of natural return, seeding and plugging is usually the most effective means of restoring a diverse native community. Managing invasives should begin before hydrologic restoration where wetland tolerant weeds are present. Otherwise, a rapid response to invasive outbreaks is important in order to prevent their spread. These are species that colonize and spread quickly, preventing the slower growing natives from establishing across the landscape. However, as the native wetland community matures, less and less invasive management will be required as the available real estate needed by invasives is colonized by natives.

At TWI’s Hennepin & Hopper Lakes project, we planted about 160,000 plants and 5,000 pounds of native seed across 1,250 acres of wetland and prairie landscape. The plants and seed included over 300 different species. This effort was designed to produce a landscape rich in species, in an attempt to approach the level of biodiversity that once was common to these diverse habitats. Ongoing invasive management is now an important part of our wetland restoration strategy.

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The Hennepin & Hopper Lakes Project near Hennepin, Illinois, is open to the public year-round, although the public access facilities are not complete. Currently there is an observation tower, limited trails, and a boat launch available to launch canoes or kayaks. Fishing is now closed. There are no permanent restrooms. Click here for driving directions or a map.

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Volunteers are always welcome. Indeed, some of the work in which we are engaged would not be possible without the valuable assistance of volunteers. We are now in the process of developing a stewardship program for those interested in taking a more active role in the Hennepin Restoration. Our most significant need is in meeting the challenge of long-term invasive species management. Although we have not previously been equipped to organize and supervise volunteers in the past, if you or someone you know has a specific interest (such as plant management or animal monitoring), please contact us and we will explore ways in which you can make a difference. Contact TWI at twi@wetlands-initiative.org

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