The Skokie Marsh

The Chicago River watershed emerged thousands of years ago and has continued to evolve through natural and human intervention.  As glaciers retreated more than 13,000 years ago, the floodwaters they unleashed pushed tons of silt and debris throughout the upper Midwest, carving out channels and leaving large deposits of sediment in ridges, called moraines, across the land.  These channels became the Chicago River and its tributaries, and the moraines created valleys that contained the water.

As the East Fork of the North Branch of the Chicago River, or the Skokie River, made its way south from its origin near present-day Waukegan, its channel became shallow and the water spread throughout the valley between present-day Highland Park and Wilmette.  The character of the marsh varied from season to season.  During the spring and summer, water levels in the marsh ranged from a few inches to several feet deep.  Cattails, swamp grasses, and other aquatic plants grew in the bog, with willow trees and bunch grasses creating small islands.  White oaks and maple groves dotted the landscape, especially to the west of the marsh.  Peat deposits as deep as five feet covered much of the swampland.  The lush vegetation of the Skokie Marsh provided habitat for a variety of wildlife.  Thousands of birds, including meadowlarks, woodpeckers, bluebirds, owls, and herons found homes and forage in the marsh.  Small mammals, such as rabbits, muskrats, and weasels lived among the cover of the tall grasses.  Bass, catfish, and perch, along with various crustaceans swam in the shallow water.

The landscape changed dramatically in the fall and winter.  Lower water levels caused the peat and grasses to dry out, making slow-burning fires a common occurrence.  In the winter, water froze over the marsh as bitter winds swept across the bleak landscape.  This diverse ecosystem was growing and changing long before anyone conceived of creating the Skokie Lagoons.