Duncan

Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Duncan Lake on August 11th, 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 (Cisco, also known as 'Tullibee', are also present). 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, the water temperature decreased below 8.8 degrees C (47.8 degrees F) at 31.4 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 103.1 feet at the time of sampling. The thickness of this layer of water in the water column was 72.1 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 4.7 degrees C (40.5 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 2013 and 2023 also indicate suitable oxythermal habitat in all years surveyed When adequate oxythermal habitat is unavailable, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Duncan Lake on August 11th, 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 (Cisco, also known as 'Tullibee', are also present). 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, the water temperature decreased below 8.8 degrees C (47.8 degrees F) at 31.4 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 103.1 feet at the time of sampling. The thickness of this layer of water in the water column was 72.1 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 4.7 degrees C (40.5 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 2013 and 2023 also indicate suitable oxythermal habitat in all years surveyed When adequate oxythermal habitat is unavailable, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Duncan Lake on August 11th, 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 (Cisco, also known as 'Tullibee', are also present). 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, the water temperature decreased below 8.8 degrees C (47.8 degrees F) at 31.4 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 103.1 feet at the time of sampling. The thickness of this layer of water in the water column was 72.1 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 4.7 degrees C (40.5 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 2013 and 2023 also indicate suitable oxythermal habitat in all years surveyed When adequate oxythermal habitat is unavailable, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Based on Minnesota DNR survey data, anglers target Yellow Perch and Lake Trout in Duncan. See the full species list above for catch rates, size structure, and quality scores.

We don't have a confirmed public access point on record for Duncan. Check the DNR LakeFinder page for current access details before you go.

Duncan has a maximum depth of 130 feet and a mean depth of 46.8 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Duncan is from 2018. Surveys this old should be treated with some caution — fish populations change over time.

No invasive species are on record for Duncan in Minnesota DNR data. Always clean, drain, and dry your equipment to help keep it that way.