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The Northerly Island is a 91-acre manmade peninsula found on the shores of Lake Michigan in Chicago, Ill. It is located south of the Adler Planetarium and provides protection to Burnham Harbor from Lake Michigan storms. The restoration would primarily occur on the south side of the island and encompass approximately 40 acres of land. From 1947 to 2002 the island was home to a small airport known as Meigs Field. Today, the northern end of the island is occupied by a music venue, Charter One Pavilion. Northerly Island’s unique location and vicinity within Lake Michigan provides an ecological refuge to a variety of organisms in an otherwise urban environment.
The project includes the following features:
Site Preparation – The first task would be to install safety fencing and other safety features in order to keep the public out of the site during heavy construction. Staging areas and access roads would be demarcated. All surficial infrastructure and ornaments would need to be removed and discarded or stockpiled and saved depending on the Chicago Park District's (CDP) needs and desires.
Geomorphic Contouring – Once the site is ready for grading, the geomorphic features would be created. This grading would establish the hydrologic regime according to the particular native plant community the contours delimit. All unsightly material that is not suitable for growing plants on or habitat would be reburied sufficiently beneath the mesic prairie and savanna plant communities; since these two community types would not be affected by conglomerate materials. About 260,000 cubic yards will be pushed around the site to achieve design contours.
Substrate / Amendment Placement – Pond and lake substrates would be placed as soon as grading is complete. About 6,600 cubic yards of mixed sand and alluvial gravels would be placed in a 1” thick layer within the pond. It is expected for emergent vegetation to creep down into some of the pond slops to further stabilize the pond banks. Limestone flags would be used as mudpuppy habitat in the bottom of the pond around 4” deep and in areas along the bank where stabilization enforcement may be need. The mouth of the pond, where it connects to the lake, would also have a galvanized steel mesh fence that will rise just above the water line to prevent large invasive species such as common carp and non-native Salmonids from entering the pond ecosystem.
Materials for the Lacustrine restoration would be placed by small barge. The jersey barriers would be set up first as a retaining wall, then back-filled with a band natural rounded cobbles for lithophilic spawners and a band of sandy silt for submergent macrophyte establishment that are both 1” thick. A temporary (5-year) adult common carp barrier (fence/net) would be placed around this area to prevent uprooting the young macrophytes prior to establishing.
Once grading is complete, to ameliorate the unnatural soil conditions of the site for proper biogeochemical cycling, a soil amendment consisting of leaf compost will be incorporated into the top 6” of soil for emergent marsh and wet prairie communities. Incorporating a soil amendment will decrease bulk density and increase soil organic matter, while enhancing microbial communities and stimulating vegetative diversity.
Native Plant Community Establishment – The finishing touch of the project would be to establish native plant communities over the remainder of the construction period. These communities would be located according to the new hydrogeomorphology, soils and substrates established by the previous steps. Once in the second year of restoration and the initial seeding complete, the site may be open back to the public since very few activities would be occurring, which are considered low impact. These include spot herbicide application and planting native plugs, which are very similar to home gardening activities.
Recreational Features – Components of recreation are not proposed under this project. The CPD has coordinated its passive recreational feature plans which include signage, mowed pathways, small board walks, and a small one acre mowed camping zone. None of these features would affect expected ecosystem benefits.
project cost: $9,470,000
Funding of this project is through U.S. Environmental Protection Agency’s Great Lakes Restoration Initiative (GLRI). GLRI priorities include cleaning up toxics and areas of concern, combating invasive species, promoting near-shore health by protecting watersheds from polluted run-off, restoring wetlands and other habitats and tracking progress and working with strategic partners.
The addition of the new native habitat types on Northerly Island would provide a heterogeneous ecosystem that will promote species diversity. The project include restoring lake, and creating pond, marsh, wet prairie, mesic prairie and black oak savanna habitats for resident and migratory species of insect, fish, amphibian, reptile and bird. Each habitat type will provide important stop-over, nesting, and foraging opportunities to a unique suite of bird species. The pond, emergent marsh and lacustrine habitat would provide critical spawning habitat for many native game and non-game fishes. In addition, the aquatic plants would provide important structure and substrata for spawning fish that lay adhesive eggs and provide cover for refuge for juvenile fish. The aquatic features would also provide critical habitat for the state threatened banded killifish and the mudpuppy. These two species have been observed immediate area and have been collected throughout much of Southern Lake Michigan; this is the basis for the assumption that these species would recruit to the study area. Overall, the proposed plan will greatly benefit the overall ecological integrity of the area.
Northerly Island was opened back up to the public in September 2015 after being closed for construction. There is a concrete path that loops around the site for the purpose of maintenance that the public can use for biking and walking. Landscape fencing was installed to prevent foot traffic throughout the newly-planted areas. The site will remain open to the public during the plant establishment and maintenance activities that will continue thru October 2017. In the winter/spring of 2016, CPD closed the east portion of the path due to erosion issues. The Corps' Chicago District is working with CPD on a repair plan.