Fenske Lake is a secluded, 105-acre spring-fed lake with a maximum depth of 43 feet. It has very soft (unmineralized) water. Aquatic plant growth is sparse in the main basin, but dense in the shallow east and west end basins of the lake, growing to a depth of 8 feet. Waterlilies, watershield, and burreeds are the most common plants found in the lake. The end basins have a muck bottom, while the main basin shoreline has a boulder and rubble bottom. The inlet from Little Sletten Lake has a rocky rapids that limits fish movement; the outlet to Everett Lake has a beaver dam.
Fenske Lake's littoral zone (that portion of the lake that is less than 15 feet in depth, where the majority of the aquatic plants are found, is a primary area used by young fish, and provides the essential spawning habitat for most warmwater fishes) is 63 acres. The lake's numerous fish species include black crappie, bluegill, largemouth bass, northern pike, smallmouth bass, walleye, white sucker and yellow perch.
A lake depth map for Fenske Lake can be viewed online courtesy of the Minnesota DNR.