Millions of years ago, glaciers covered Elkhart, moved south while eroding the land and collecting glacial drift, and by 9,000 BC began retreating north, leaving behind deposits that now cover Elkhart in 122 feet of drift. Some parts of the glacier retreated more slowly, settled into clay, and formed kettle lakes with no inlets that are fed only by rainwater, which is how Boot Lake was formed. In 1955, the Indiana Department of Conservation described Boot Lake as an 80-acre lake with an average depth of 4 feet, a mud bottom, fish, and surrounding wetlands and prairies inhabited by buffalo, elk, deer, black bear, and other animals. In 1960, the City of Elkhart purchased the Boot Lake area and began using two lagoons on the property to dispose of sludge, a by-product of wastewater treatment. From 1970 to 1991, Boot Lake was used as a sludge farm. In 1985, its wetlands were registered as an Indiana Natural Area with The Natural Conservancy and IDNR. In 1991, the city began processing sludge into biosolids usable as fertilizer, and from 1991 to 1994 more than 88,000 cubic yards of sludge were removed from Boot Lake. In 1994, Elkhart EnviroCorps, an AmeriCorps National Service Organization, was formed to help restore Boot Lake, removing 40 tons of trash and creating 2 miles of hiking trails. In 1995, 20 acres of tall grass prairie were planted in June, and in July Boot Lake officially opened as a nature preserve. In 1996, a picnic pavilion shelter was donated by the Associated Builders and Contractors, and Elkhart EnviroCorps constructed a compost toilet. In 2003, Boot Lake was named a State Dedicated Nature Preserve. Elkhart EnviroCorps maintained Boot Lake until the program was discontinued in 2008. Today, Boot Lake covers 226 acres and includes more than 3 miles of hiking trails, 60 acres of tall grass prairie, 20 acres of oak savannah, and 146 acres of wetlands and woodland areas, and it is maintained by the City of Elkhart, Elkhart Environmental Division, and dedicated volunteers.