Flour

Temperature and dissolved oxygen measurements were collected from the deepest basin in Flour Lake on August 13th, 2025. This was done 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). 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 data collected from the deepest basin (maximum sampled depth was 68.9 feet), the water temperature decreased to 8.8 degrees C (47.8 degrees F) at 34.1 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 68.6 feet at the time of sampling. This layer in the water column was 34.5 feet, indicating oxythermal habitat for Lake Trout was present. 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. It is possible Lake Trout still persist in low numbers in the lake, but none were found in the previous survey. Data collected by the Minnesota Department of Natural Resources during the period of maximum oxythermal stress (July 26th to Aug 24th) in 4 years, between 1956-2023, indicated suitable oxythermal habitat in most years surveyed. There did not appear to be any suitable habitat found in the 1956 survey. When adequate oxythermal habitat is not available, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

A temperature-dissolved oxygen profile was collected in the deepest basin on Flour Lake on August 31st, 2023 to evaluate the amount of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Trout and Cisco, also known as Tullibee. Based on the profile, the top of the thermocline (i.e., the location in the water column with the sharpest transition from warm to cold water) occurred at approximately 13 feet. Dissolved oxygen decreased to below 3.0 mg/L at 76.7 feet, which was below the thermocline, at the time of sampling. The temperature at which dissolved oxygen decreased to below 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 6.3°C (43.3°F). TDO3 values cooler than 8.8°C for Lake Trout or 21.5°C for Cisco indicate that oxythermal conditions are favorable for these species. Dissolved oxygen concentrations below the thermocline indicate that suitable oxythermal habitat for these species was available across a range of depths at the time of sampling. Data collected in 1956-1994 also indicate suitable oxythermal habitat in most years, with the least favorable conditions recorded in 1956. When adequate oxythermal habitat is available, Lake Trout or Cisco are not squeezed into unfavorable, warmer water conditions and therefore do not experience higher levels of stress.

A temperature-dissolved oxygen profile was collected in the deepest basin on Flour Lake on August 31st, 2023 to evaluate the amount of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Trout and Cisco, also known as Tullibee. Based on the profile, the top of the thermocline (i.e., the location in the water column with the sharpest transition from warm to cold water) occurred at approximately 13 feet. Dissolved oxygen decreased to below 3.0 mg/L at 76.7 feet, which was below the thermocline, at the time of sampling. The temperature at which dissolved oxygen decreased to below 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 6.3°C (43.3°F). TDO3 values cooler than 8.8°C for Lake Trout or 21.5°C for Cisco indicate that oxythermal conditions are favorable for these species. Dissolved oxygen concentrations below the thermocline indicate that suitable oxythermal habitat for these species was available across a range of depths at the time of sampling. Data collected in 1956-1994 also indicate suitable oxythermal habitat in most years, with the least favorable conditions recorded in 1956. When adequate oxythermal habitat is available, Lake Trout or Cisco are not squeezed into unfavorable, warmer water conditions and therefore do not experience higher levels of stress.

Based on Minnesota DNR survey data, anglers target Smallmouth Bass, Walleye, Northern Pike, Yellow Perch, and Green Sunfish in Flour. See the full species list above for catch rates, size structure, and quality scores.

Minnesota DNR records list public access for Flour. Check the DNR LakeFinder page for the launch type and directions before you go.

Flour has a maximum depth of 75 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Flour is from 2023.

Yes — Flour has confirmed spiny waterflea. Clean, drain, and dry your equipment to avoid spreading invasives to other waters.