Generally, the Chicago River was once a sluggishly flowing marsh system that supported an immense diversity of plant and animal species. As a natural resource, it provided significant food, clothing, and building tools for American Indians and early settlers. Once the City of Chicago began to develop, the fate of the river was set in that it would soon be transformed into a conduit that would drain the surrounding wetlands and rush away storm and waste waters. The natural and anthropogenic history of the Chicago River is so diverse and rich, whole books have been written about it. The Chicago River by Libby Hill (2000) and A Natural History of the Chicago Region by Joel Greenberg (2002) are excellent resources for those interested in how the Chicago River and its watershed were transformed from its natural ecosystem into the booming city that it is today.
This photo is indicative of what the Eugene Field Park area would have looked like historically (photo by Earl E. Sherff “Vegetation of the Skokie Marsh” early 1900s). The natural condition of the Chicago River North Branch and its riparian plant communities within the vicinity of the modern day Eugene Field was a broad, sluggishly flowing marsh system that was confined by the Park Ridge Moraine to the west and the Rose Hill and Graceland sand spits to the east. The marshy plant communities were predominately reeds, sedges, rushes, and other hydrophytic plants. Native shrub patches would form in the slightly higher elevation areas and trees were quite minimal in this ecosystem (Pepoon 1927, Swink & Wilhelm 1994, Libby 2000).
It was fortunate from a habitat restoration perspective that Eugene Field Park was minimally disturbed from its natural state. The North Branch of the Chicago River in the Eugene Field Park reach was probably straightened and deepened between 1904 and 1907 so the river’s surrounding land could be used for farming and residential homes. According to a General Land Office mapping, not only was the river channelized, but it was moved as well to accommodate building plans. Also, the bottom of the river through Eugene Field Park was paved with concrete, and still is, to shuttle water downstream faster. This action drained away the land and subsequently the marshes disappeared. The Eugene Field Park and its surrounding residential neighborhood were probably built between 1905 and 1930. Most of the residential buildings date from the early 1920s. The southern bank of the new river channel was created out of concrete blocks and steel sheet piling, with the fill material behind the walls containing pre-WWII glass and ceramics. This wall was built as part of the WPA Program in the 1940s. The north side of the river may have been only lightly farmed or used for small spoil piles, but for the most part it was spared the massive alteration that the surrounding land experienced. The two habitat types that existed naturally at the Eugene Field Park were oak savanna and marsh; one can see the remnant oaks in the Cemetery just across Foster Avenue to the north. The Eugene Field Park retained a sliver of this, with about 5 giant mature white oaks (Quercus alba) still standing as historic sentinels.
In the 1970s, the park and surrounding neighborhoods began to experience flooding due to the upper parts of the watershed becoming developed. This measure was still not enough to reduce flooding, so in 1988, the USACE Chicago District was requested to engage in a Section 205 Flood Control study, Monticello Avenue. A plan was recommended, but due to the public not fully supporting the plan, the study was terminated. In 2002, the Chicago Park District requested the USACE Chicago District to undertake a feasibility study to determine if it was possible to restore wetlands within the Eugene Field Park. The impetus behind this request was that the northern portion of the park experienced frequent flooding and that subsurface groundwater would keep the area saturated a good portion of the year.
In 2007, the Chicago Park District and the US Army Corps of Engineers completed a feasibility study to restore half of Eugene Field Park to closely mimic the former habitat that occurred there, but also to open the Chicago River to the public. The above photo illustrates how during the summer the river is inaccessible physically and visually. In additional to ecosystem objectives, this project incidentally would remove 10,000 cubic yards of fill from the floodplain, which would allow for the site to store more water during flood events.
The restoration project commenced in April 2011. The first phase was to remove non-native and weedy trees from the site. This was done to a) eliminate non-native and invasive plant species effects on native plant and animal communities, b) to help reestablish hydrology and c) to allow for the removal of unnatural fill that was formerly placed in the marsh. Large tree removal targeted only those trees that were not native to the area or not indicative of the historic marsh or oak savanna habitats. Other trees removed along the bank of the Chicago River included Siberian elm, weeping willow, tree of heaven and silver maples. These trees have the ability to both lower ground water hydrology and prevent the growth of native understory shrubs and herbaceous plants. At no point were any oak or savanna tree species removed from the site.
This cottonwood removed from Eugene Field was about 40-years old based on its growth rings; whereas the same size white oaks that remain on site are well over 150-years old. The wider the growth rings on the tree, the faster they grew that particular year. Cottonwoods are floodplain pioneer species that quickly colonize and grow on newly formed point bars of meandering rivers.
The remnant oak savanna in the background was marked off with orange snow fencing to protect the ancient oaks that were retained on site. Also, a whole grove of cottonwoods were retained on the eastside of the park that were not part of the habitat restoration per say, but they do provide buffer to the site.
The second step was to place two large boulder and cobble riffle structures in the Chicago River. These riffles are placed in a slightly concave fashion to direct the water flow towards the center of the channel. This is done in urban streams that no longer meander or have natural sediment transport functions. In addition to stabilizing banks upstream of the riffles, these structures also provide critical habitat for macroinvertebrates and fishes. The most important aspect of these riffles is that overtime it will cause the bed of the stream behind the riffle to accumulate sand, gravel and other alluvial materials, thusly restoring channel geomorphology, again providing important aquatic habitat. This desired effect will be very difficult to achieve and may take longer in this section of stream due to the fact that the bottom is paved with concrete.
Next, the site was graded to the specified geomorphology that would restore a marsh basin, lessen the steepness of certain bank areas, and remove the unnatural fill that covered the natural wetland soils beneath. Existing sites that are cleared of their existing invasive species usually look very devastated for the first year or two of the project. This is due to the drastic changes that need to occur in order to shift the system back into a more natural hydro-geomorphic setting. When man converted natural areas for various uses, the geomorphology and underlying hydrology are usually eliminated , which is the case for the entire Chicago River in Cook County. This is one of the primarily reasons that the open space along the Chicago River is dominated by tolerant native and non-native trees, shrubs and grasses.
The summer of 2011 was the first full growing season. The whole site was seeded with a couple different plant community mixes. The above photo shows the remnant white oaks where a native oak savanna species mixed was sown. Different seed mixes were developed for the banks, the wetland basin, the transition slopes of the wetland basin, and the oak savanna. Most of these plants sown from seed will take awhile since prairie plants establish their root systems first for a couple of years before they grow skyward.
Once the regular mowing under the oak trees stopped to allow seeds to germinate and grow, sapling white oaks began to establish. There will be no need to plant oak trees for this project since natural recruitment is expected and welcomed.
A year later, in the late spring of 2012, it was time to plant live plugs to supplement the seeding. Live wetland and mesic savanna plants were plugged throughout the site and maintained by the contractor.
Fall of 2012 rolled around and it was time to sow more seeds to bolster the densities throughout the site. The plugs planted in spring did well and were going dormant for the year. This second round of seeding focused intently on the banks of the Chicago River in a few areas that were experiencing bare ground. The strings and stakes throughout the site prevent Canada geese from eating newly planted live plugs.
And with fall come the big bucks. This large male deer was chasing around a doe along the bank of Eugene Field Park with complete disregard for the contractor, whom was concurrently sowing seeds.
Late winter 2013. The little stakes in the wetland area are to keep the geese from eating the plants until the plant community is established as a whole.
Late spring of 2013. This poor little burr oak did not make it. Although some thought it would be nice to have a different species of oak, it is most likely too wet at this site for bur oaks. The white oaks will naturally spread from the remnant savanna on site and from across Foster Avenue throughout the rest of the site since they are better adapted for the sites hydrology. Squirrels naturally help distribute and plant the white oak acorns as well. As a note, if oaks are going to be planted for restoration purposes, none of the branches should be pruned by the nursery, as the one in the picture shows. Oaks should have branches that touch the ground when they are this young.
The rain waters in 2013 helped the site out greatly, especially the transitional zones of the wetland basin. The bur reeds and pickerel weed are coming back from being planted the previous spring.
After two years of growth and adaptively planting the banks, they still look a bit peaky the day this photo was taken in the spring of 2013. It is very difficult to grow native plants indicative of the historic system on the banks due to the Chicago River’s poor water quality and flashy bounces due to an impervious surface laden watershed.
Adaptively managing the plant species along the bank finally worked in the summer of 2013. Native vegetation now covers the banks down to the toe.
In the late summer of 2013, this is what the Eugene Field Park looks like. This piece of land was once a marsh, then drained and filled in, then turned into a park, then tore apart to reestablish hydrogeomorphic characteristics, and finally returned to resemble its former beauty. All the plants seen in this wetland area are native, with a sentinel white oak in the background.