From its headwaters near Waukesha, Wisconsin, the Fox River drains 938 square miles in southeastern Wisconsin prior to entering Illinois.
Between the McHenry County/Wisconsin border and its junction with the Illinois River near Ottawa, the river runs for 115 miles and drains an additional 1,720 square miles. Although it is only 3% of the total area in Illinois, the watershed is home to nearly 1 million people; a number that is likely to increase in the coming years.
The Fox River is a multi-purpose resource that contributes critical habitat for wildlife, serves as a valuable resource for recreation, receives and assimilates pollutants from point and non-point sources and provides source water for public water supplies. Habitat modifications may also play a significant role in the dynamics of the river. Because of the rapid pace of development in the Fox River watershed, maintaining these resources requires comprehensive planning.