Heidecke Lake, located in Grundy County, Illinois, is a 1,955-acre former cooling reservoir that now serves as a prime fishing destination. While the lake offers excellent angling opportunities, it is important to note that paddling activities are not permitted. Only boats with gasoline-powered motors as the main propulsion unit are allowed for fishing or waterfowl hunting purposes.

The lake features 17 miles of shoreline, with 75% comprised of rock rip-rapped dikes. A "safe harbor" created by breakwaters was constructed in 1993. The average depth is 9 feet. Shore angler access is available on the east side of the lake off Dresden Road, with portions of the center and east dike open to bank fishing. A handicapped-accessible fishing pier is located on the east side.

Heidecke Lake is open for fishing from April 1 until 10 days before the opening of the Northern Zone Duck Season. Operating hours are from 6:00 a.m. until sunset. The lake is closed to all activities when wind speeds are projected to be 25 mph or greater, as windy conditions can produce treacherous waves.

Adjacent to Heidecke Lake is Goose Lake Prairie State Natural Area, one of the largest prairie remnants in Illinois. This 2,527-acre area provides habitat for various wildlife, including ducks, geese, rare Henslow's sparrows, and larger animals such as deer and coyote.

Facilities include a recently refurbished three-lane concrete boat ramp with fully blacktopped parking for over 100 cars and trailers. A Visitor Center at Goose Lake Prairie offers nature displays and multi-media presentations to enhance understanding of the local ecosystem.

It's crucial to emphasize that swimming, wading, water skiing, and sailboating are strictly prohibited on Heidecke Lake. Visitors should be aware that zebra mussels have been found in the lake, and appropriate measures should be taken upon departure to prevent their spread.