Wetland Restoration: Part 2, Reading the Landscape (from online to on-site)

Does your property have wetland restoration potential? Part 1 of this Wetland Restoration series highlighted the four-step process the U.S, Fish and Wildlife Service (USFWS) Partners for Fish and Wildlife Program (PFW) biologists utilize to assess a property for wetland restoration potential (with online resources). Turning this online potential into on-site reality is a process, too. Part 2 will discuss characteristics on the landscape that help determine the restoration techniques and processes best suited for your project site.

The goal of a wetland restoration is to return and maintain shallow water on the land. Equally important is returning and maintaining the moist-soil vegetation (also known as duck food). Typically, if you can return the shallow water, the moist-soil plants will come back naturally. PFW biologists use a variety of techniques to restore the water and plants previously removed from a wetland basin. Wetlands have historically been removed from the landscape for agriculture or development, and since the 1780s, Illinois has lost 90 percent of its wetlands. Over the years, wetlands have been filled in, punctured, ditched and tiled to remove water. Before restoration can begin, a PFW biologist examines the land use history of a potential project site and visits it to see what clues on the land itself may tell them.

There are a variety of features on the landscape that help a PFW biologist determine which type of restoration technique is best for each project site. Often, a biologist can see subtle changes in vegetation and topography that indicate where a wetland has once been. Water-loving plants and shallow depressions are two features that help determine the extent of a wetland basin and direct a biologist to look for more clues to guide the restoration process.

Once a basin has been found, a PFW biologist looks for signs of land alteration and drainage. In some instances, wetlands were filled in or silted in, and wetland restoration may be as simple as removing a few inches of soil to restore a natural shallow basin. To determine the amount to be removed, a soil core may be taken to find the depth of hydric soils and ground water. An onsite elevation survey is also key to wetland restoration design. Most of these “scrape” designs call for 6 to 18 inches of soil to be removed with an average depth of 12 inches (the perfect depth for moist-soil plants and foraging ducks). These designs also call for very gradual side slopes, microtopography on the bottom and small islands. All these features promote good moist-soil vegetation (duck food), waterfowl and shorebird accessibility, and good nesting and brood-rearing habitat.

At other sites, the original rim of the wetland basin may have been cut or lowered to drain the wetland. Alterations to the wetland brim may be an obvious change in elevation around the edge of the basin, or a slight linear channel leading water downhill. In either case, a PFW biologist may design a small berm to restore the rim of the wetland and allow water to pool once again. Typically, these types of projects require minimal amounts of dirt-moving to bring back very high-quality wetlands.

Perhaps the biggest indicator for restoration potential are drainage ditches and old tile lines. Small ditches, tile inlets, tile holes, or tile blow outs (where failed tiles may force water to the surface) can usually be traced to a wet spot on the landscape. Though they may be easy to spot, these often require several techniques to restore the wetland hydrology. For example, ditches may be plugged or redirected. If so, a PFW biologist may decide a water control structure should be installed to best suit habitat management needs and the landowner’s habitat goals. In most project sites, existing drainage tile will be removed to restore hydrology. At some project sites, however, PFW have installed water control structures on existing agricultural drainage tile to impound seasonal water. Water control structures are a great tool for biologists and land managers. They allow manipulation of water levels for moist-soil vegetation drawdowns, and most importantly, they help to lower water to control unwanted vegetation when needed. Wetlands are great, until they are full of phragmites, reed-canary grass and narrowleaf cattails (more information on this in Part 3).

Each wetland restoration design is different, driven by the clues a PFW biologist finds during their site visit. Depth vs size vs drainage area all come into play on project design. If there is one key component in these designs, it is the importance of shallow water.

Once the design is in place, the biologist works directly with local equipment operators throughout the wetland restoration process. In nearly all the wetland restoration scenarios, we start with exploratory trenching for tile investigation (also known as trench rings). There is a spiderweb of old drainage tile underneath the Illinois landscape going all the way back to the early 1900s. Missing one of these 4 to 6 inch old clay tiles is easy to do and can cause a great project to remain dry. Another small, but crucial component to project success is ensuring that the dirt-moving equipment is clean of invasive seed and residue before coming onto a new site. There is nothing worse than accidentally turning a beautiful stand of sedges, rushes, smartweed and barnyardgrass to a field of phragmites, reed-canary or narrowleaf cattails.

In the next and final part of this series, we’ll wade into wetland management. We will discuss the benefits of native moist soil plants, manipulating water levels and reducing the presence of undesirable vegetation.

If you’re interested in restoring wetlands in east-central Illinois, contact Jason Bleich at jason_bleich@fws.gov to get started. If you’re interested in restoring wetlands in the Illinois River Valley or western/southwestern Illinois, contact Emily Hodapp at emily_hodapp@fws.gov. If you’re interested in restoring wetlands in northwestern/northern Illinois, contact Scott James at scott_james@fws.gov.

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Jason Bleich is a Private Lands Biologist for the U.S. Fish and Wildlife Service (USFWS) in Illinois. He has worked with private landowners the majority of his 13-year career in natural resources, including Pheasants Forever and the Ford County Soil & Water Conservation District. Originally from Illinois, Bleich has had the opportunity to work in multiple states including Arkansas, Iowa, and Missouri before returning to his hometown in east-central Illinois. Bleich is excited to continue working with Illinois landowners and conservation partners in his role with the USFWS Partners for Fish and Wildlife Program.

Emily Hodapp is a Private Lands Biologist for the U.S. Fish and Wildlife Service in Illinois. Hodapp works with conservation partners and landowners throughout the Illinois and Mississippi rivers areas to produce more duck food while also promoting Boltonia decurrens, a federally threatened plant species. In addition to her work on the rivers, she tackles hill prairie restorations which benefit the monarch butterfly, pollinators, northern bobwhite, migratory songbirds and more.