Waterfall Glen Forest Preserve is a forest preserve in southern DuPage County, Illinois. It is known for its waterfall, which actually is a dam, which is in its ravine. It completely surrounds Argonne National Laboratory. It is also home to a popular model airplane field, located in the southwest section of the forest preserve. Hikers can also make the interior trip to St. Patrick Cemetery nestled deep in the preserve. The 2,492-acre Waterfall Glen Forest Preserve in Darien is an ecological parcel of open space within the Forest Preserve District of DuPage County.
Waterfall Glen's prairies, savannas, and oak-maple woodlands contain 740 native plant species, 75 percent of all the plants known to grow naturally in DuPage County. There are over 300 species of mammals, birds, fish, amphibians, and reptiles and another 300 of invertebrates use the forest preserve either year-round or during their migrations.