Douglas Lake, located in Cheboygan County, Michigan, has been defined as a moderately eutrophic lake (Bazin and Saunders, 1971). The lake was formed during the late glacial period. As the Wisconsin ice sheets receded, seven or more blocks of ice were left buried in the earth where Douglas Lake now exists. The melting of these ice blocks left seven deep basins which led to the formation of the lake. The deepest of these basins is located on the west side of Pells Island. Other deep depressions are located around South Fishtail Bay (24.1 m deep), and the northwest corner of the lake just west of Roberts Point. These deep holes are broken up by broad shoals where the water is shallow, creating a very diverse lake habitat. This type of lake is technically called a kettle hole lake (Welch, 1935).http://deepblue.lib.umich.edu/bitstream/2027.42/54355/1/2791.pdfDescription of 2791.pdf : Access restricted to on-site users at the U-M Biological Station
