Four soft water seepage lakes, each separated by an isthmus are the main features of the natural area. The lakes are Bittersweet (104 acres, 31 feet), Oberlin (46 acres, 25 feet), Smith (43 acres, 18 feet), and Prong (30 acres, 50 feet), and all have a variety of bottom substrates, ranging from sand and gravel to rock and muck, are slightly acidic, and have relatively high water clarity. Water levels fluctuate slightly each year. The aquatic vegetation consists of many unusual plants including seven-angle pipewort, watershield, bur-reeds, golden pert, quillworts, water lobelia and waterweed. In some areas, lake pockets contain leatherleaf dominant bog vegetation. The shoreline vegetation consists of a narrow zone of shrubs such as leatherleaf, alders, and meadowsweet, which changes abruptly to uplands. Northwest of Smith Lake and west of Oberlin Lake is an old-growth northern mesic forest remnant of hemlock and yellow birch; a black spruce-tamarack bog is located west of Smith Lake. White pine, red oak and birch dominate the forest found between Bittersweet and Prong Lakes, and a second-growth northern dry-mesic forest composed of paper birch, aspen, red maple, red oak, and lesser amounts of white pine, occurs in other areas. The fishery consists of walleye, northern pike, large and smallmouth bass, and panfish. Many diving ducks use the lakes during migration and common loons have nested in the tract. Bittersweet Lakes is owned by the DNR and was designated a State Natural Area in 1958.
