The Forest Preserves is performing a comprehensive restoration of the 528-acre Tinley Creek Ravines starting in fall 2019. Served by the Catalina Grove Family Picnic Area parking lot and bounded by 143rd St, Harlem Ave, 151st St and 80th Ave, this area represents one of the highest priority sites for ecological restoration in southwest Cook County. The goal of the restoration is to create a mix of healthy oak woodland and restored prairie that can be sustainably enjoyed by the public.
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Tinley Creek bisects the area, flowing from west to east toward the Cal-Sag Channel. A network of ravines and intermittent streams feed the creek, creating a unique landscape. Most of the ravines contain remnant oak-hickory woodlands that appear to have escaped plowing or logging, though nearby farmers may have grazed cattle here before this land became a forest preserve.
Today the woodlands retain a canopy of mature oaks, but due to decades of fire suppression the understory beneath these oaks is dense with ironwood, sugar maple and hickory tree saplings. The unnaturally high tree density crowds the natural spread of the oaks’ limbs and limits the amount of light reaching the ground. Without sufficient light, native plants that support insects, birds and other wildlife cannot thrive here.
Without a sufficient ground-layer of native plants, topsoil washes away as water flows into the ravines. An extensive network of unofficial foot and bike trails has worsened the erosion.
Other portions of the site were disturbed by farming and currently contain a mix of non-native grasses, scattered prairie plants and woody vegetation.
Fortunately, the woodlands still contain pockets of high-quality ground-layer vegetation, an indication that with ecological management the Forest Preserves can restore the Tinley Creek Ravines to a healthy, diverse woodland that supports a robust ecosystem of native plants and animals.
The Forest Preserves Resource Management Department is coordinating and managing this project. Under their direction, contractors are thinning unnaturally dense native trees and removing invasive tree and brush species from approximately 500 acres of woodland. This work will restore a diverse ground layer of plants, enhance native wildlife habitat, reduce erosion and allow the soil to absorb more stormwater.
During growing seasons, Forest Preserves staff and contractors will conduct follow up vegetative and woody invasive species control.
The Forest Preserves will also address areas of excessive erosion through hydrologic repairs and design a less-damaging informal trail network through the preserve.
The restoration work is scheduled to start in fall 2019 and continue through 2024.
Funding & Water Main Project
This project is creatively funded through a partnership with the Oak Lawn Regional Water System, which serves 12 suburban municipalities (Country Club Hills, Matteson, Mokena, New Lenox, Oak Forest, Oak Lawn, Olympia Fields, Orland Hills, Orland Park, Palos Hills, Palos Park and Tinley Park) in southwest Cook County.
As the lead municipality for the water system, the Village of Oak Lawn applied for a license to locate approximately five miles of new water main through the ComEd utility right-of-way that includes a section that bisects the Tinley Creek Ravines area. The new water main would extend from 131st St and 76th Ave in Palos Heights to the north to 163rd St and Central Ave in Oak Forest on the south.
While the water main project will temporarily disrupt portions of the Tinley Creek Trail System, the license fees will cover the costs of Tinley Creek Ravines restoration work and the relocation of portions of the Tinley Creek Trail System to the ComEd utility right-of-way.
The Forest Preserves believes the benefits to the 528-acre Tinley Creek Ravines and the Cook County residents served by the water main project will be worth the short-term impacts.