Ten Mile Lake is a deep, large, clear-water lake located just north of Hackensack, Minnesota and just southwest of Leech Lake. It has moderate residential development on all shores, currently sees heavy recreational use, and is a popular destination. Its watershed is small relative to its surface area, with a ratio of 5:1 with land use dominated by forests and water/wetlands, typical of a north-central Minnesota lake. The lake contains a number of rocky reefs and shoals, sand and gravel points, large areas of open water, and weedy shallow bays. It is one of the deepest natural lakes entirely within the state.
The aquatic plant community is very species-rich, yet interestingly, only one species of Chara was found at more than ten percent of the sites. Chara is an architecturally complex species that provides quality habitat for juvenile fish and is an important resilience mechanism in lakes that maintain high water clarity.
Ten Mile Lake has a wide variety of habitats that support a diverse fish community including Walleye, Northern Pike, Largemouth Bass, Smallmouth Bass, Bluegill, Black Crappie, and Yellow Perch. The lake also harbors two cold-water fish species, Lake Whitefish and Cisco, which inhabit the deeper pelagic areas of the lake. In fact, Ten Mile supports the highest quality population of Lake Whitefish of all 25 Sentinel Lakes, with high abundance and exceptionally long lifespans. Individuals up to 62 years of age have been sampled and the average age of sampled adult Lake Whitefish is between 20 and 30 years old. The Cisco found in Ten Mile are a dwarf variety, with adults rarely exceeding 15-18 cm in length. Unfortunately, the status of Lake Whitefish and Cisco are uncertain because traditional survey gears do not target these populations. The Sentinel Lakes program has begun conducting hydroacoustic and vertical gillnet assessments targeting these species, with additional refinements planned for the future.
Ten Mile Lake was selected as a Sentinel Lake because it is an example of a deep, mesotrophic lake in the Northern Lakes and Forests ecoregion with a high species diversity. Additionally it has a long history of water monitoring.