Lake Mille Lacs 1992 Clean Lakes Study (314a) Water Quality Report

Lake Mille Lacs is located in east central Minnesota in Aitkin, Crow Ving, and Mille Lacs counties (Figure 1). The lake was formed during the Wisconsin glaciation and is an excellent example of a moraine-dam lake (Zumberge, 1952). The rugged Mille Lacs moraine forms the western and southern boundaries of the lake and rises rather sharply more than one hundred feed above the lake's surface near the community of Garrison. The north and east shores of the lake are generally low and marshy, indicating a former lake level some 15 feet above the present. The lake basin encompasses approximately 207 square miles and has a shoreline of approximately eighty miles (Table 1). The shoreline soils are of a sandy or rocky nature. The lake substrate ranges from rock, gravel, and sand in the shallow areas to sedimented deposits (muck) in the deeper, center portions. Because of its size, bathymetric data for the lake is incomplete; however, it is believed to have a maximum depth of 43 feet (13 m) and a mean depth of 21 feet (6.4 m). The Lake Mille Lacs watershed covers approximately 417 square miles (LMIC/MDNR, 1993), of which 55 percent is lake surface (Figure 2). Land use in the watershed is approximately 20 percent agriculture and 70 percent hardwood-coniferous forest and marsh.