Along the east branch of the DuPage River lies the 266-acre Whalon Lake, acquired between 1992 and 1994. The preserve features an oak-savanna grove and large wetland areas that have been restored and enhanced, in addition to a variety of recreation opportunities. 

The western portion of the preserve includes a picnic shelter that can be reserved for large groups. It also contains an eight-acre dog park with a smaller 2.5-acre park for dogs under 30 pounds. A permit is required for dog park use.

The eastern portion of the preserve features an 80-acre converted quarry lake that offers canoeing, kayaking, and boating opportunities. A 1.85-mile paved trail, part of the multi-jurisdictional DuPage River Trail, encircles the lake. The trail continues 0.5-mile west beyond the dog park to the wetlands; this trail is ideal for hiking, biking, in-line skating, and cross-country skiing.

The lake is stocked with largemouth bass, bluegill, channel catfish, and crappie for Catch and Release fishing. Taking frogs, turtles, and mussels is prohibited. An Illinois fishing license is required for anyone at least 16 years of age who fishes a public Illinois waterway, and may be obtained from the Illinois Department of Natural Resources. Only two pole and line fishing is allowed. Ice fishing, swimming, wading, and dogs in the water are prohibited. All statewide fishing regulations apply.