Lyon Lake is a small, natural lake in Fredonia Township, Calhoun County, Michigan. The lake is approximately ³⁄₄ mi (1.2 km) long and ¹⁄₄ mi (0.40 km) wide (125 acres (51 ha)). The lake is part of a small cluster of lakes 6 mi (9.7 km) south of the historic village of Marshall, Michigan.