Alder Lake

Cook County, Minnesota - DNR stocking history, depth and survey data

Minnesota · Minnesota Department of Natural Resources (DNR) · DOW 16011400

Alder Lake has no DNR stocking rows in LakeFinder; this page carries its DNR depth, access and survey data.

• Alder Lake shows no stocking records in Minnesota DNR LakeFinder as of September 2, 2026.
• Maximum depth 72 ft; surface area 529 acres, 132 littoral acres, 10.0 miles of shoreline, per the DNR lake survey.
• Average water clarity (Secchi depth) 14.2 ft.
• Fish species DNR lists here: green sunfish, hybrid sunfish, lake trout, northern pike, smallmouth bass, splake, walleye, white sucker, yellow perch.
• 1 public access on the DNR list.
• Most recent DNR fish survey: August 13, 2025 (targeted survey).
• Cook County, nearest town Grand Marais; DNR lake number (DOW) 16011400.

Depth map

Bathymetric contours from the Minnesota DNR lake survey mapped 1/1/1940 (orig map); depths in feet. Simplified for the web; not for navigation.

Public accesses

DNR fish survey, 2025

Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Alder Lake on August 13th, 2025, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Trout, the most sensitive coldwater species present in this lake. During the summer, Lake Trout require a layer of oxythermal habitat that contains water temperatures below 8.8 degrees C (47.8 degrees F) and dissolved oxygen concentrations above 3.0 mg/L. Based on the profile from the deepest basin (maximum sampled depth 52.5 feet), the water temperature decreased below 8.8 degrees C (47.8 degrees F) at 29.2 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 50.9 feet at the time of sampling. The thickness of this layer of water in the water column was 21.7 feet, indicating that oxythermal habitat was present for Lake Trout. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 7.3 degrees C (45.1 degrees F). TDO3 values cooler than 8.8 degrees C (47.8 degrees F) indicate that oxythermal conditions were suitable for Lake Trout at the time of the survey. Data collected by the Minnesota Department of Natural Resources during the late summer period of maximum oxythermal stress (July 26th to Aug 24th) in 4 years, between 1988-2024, indicate suitable oxythermal habitat in most years when surveyed, with the least favorable conditions recorded in 2024 when adequate oxythermal habitat was unavailable. Reviewing recent data, Alder lake has TDO3 measurements ranging from 6.8 to 9.8 degrees C. When adequate oxythermal habitat is unavailable, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Minnesota DNR survey narrative, August 13, 2025.

All Minnesota stockings · every Minnesota lake with a page · state CSV · this lake on DNR LakeFinder