Saganashkee Slough-McMahon Woods

Section 506, Great Lakes Fishery & Ecosystem Restoration (Section 506 WRDA 2000, as amended) 


The Saganashkee Slough-McMahon Woods is a portion of a greater natural area, called Palos Preserves (~6,000-ac), primarily owned and managed by the FPDCC. The study area is within the historic boundary of the Great Lakes basin and borders the Calumet-Saganashkee (Calumet-Sag) Channel near Palos, Ill., in Cook County. The Forest Preserves of Cook County has in turn requested that the Chicago District, US Army Corps of Engineers (USACE) initiate a study under the Section 506 Great Lakes Fishery and Ecosystem Restoration (GLFER) authority to determine the feasibility of restoring important critical wetland and wildlife habitat within Saganashkee Slough-McMahon Woods. Preliminary evaluation of the project site resulted in the removal of the Saganashkee Slough portion of the study area because of the high cost to implement measures to address fish habitat problems and concerns from the FPDCC. This report has evaluated the feasibility and environmental effects of restoring geomorphic features, hydrology, marsh and wooded riparian plant communities within McMahon Woods. The scope of this study addresses the issues of altered geomorphology, absence of native plant communities, invasive species, fire suppression, rare wetland/fen communities, degradation of critical habitat for a federally listed species, and poor quality native plant communities.


Total Project Cost:


Federal Cost:


Non-Federal Cost:


*Non-federal sponsor will reimburse their 35% of the feasibility study cost after signing the project partnership agreement if project gets funded. 

**This project was partially funded with Great Lakes Restoration Initiative (GLRI) funds received from U.S. Environmental Protection Agency.


The feasibility study and supporting documentation was sent out for a 30-day public review in November 2015. The feasibility study was approved in February 2016. The project is on hold due to lack of federal funds.

The McMahon Woods study area is approximately 410.6-acres of publicly-protected lands within the Palos Preserves area of the Forest Preserves of Cook County. About 300 acres of the study area is designated critical habitat for the Great Lakes subpopulation of Federally Endangered Hine’s Emerald Dragonfly (Somatochlora hineana). McMahon Woods is located along the Lake Michigan Flyway, which a part of the greater Mississippi Flyway. The Lake Michigan Flyway is notable as one of America’s most important migration routes for songbirds. Songbirds and other groups of birds (e.g., shorebirds, raptors, etc.) migrate from South America to breed in portions of the Upper Midwest all the way to Canada and Alaska. It is critically important to migratory birds that use the Lake Michigan flyway to have optimal stopover habitat and food resources to successfully complete their migration. The shoreline of Lake Michigan and its surrounds, which includes northeast Illinois and McMahon Woods, provides vital natural areas that offer rest and foraging opportunities for tired and hungry migrants.  

Problems within the study area include alteration of hydrology, geomorphology and loss of coverage of native plants. This has resulted in the overall degradation of the native plant community, decreased suitability of wildlife habitat, and a lack of suitable habitat for state endangered and threatened plant species to expand their range within the project area.  Most notable is the continued degradation of a federally endangered species habitat for the Hine’s Emerald Dragonfly.