Iron

Temperature and dissolved oxygen measurements were collected on August 14, 2024 in two locations in Iron Lake: the deepest basin, WQ1, just downstream of curtain falls, and in a deep hole on the west side of the lake, WQ2, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in this lake. During the summer, Cisco require a layer of oxythermal habitat that contains water temperatures below 21.2 degrees C (70.2 degrees F) and dissolved oxygen concentrations above 3.0 mg/L. Based on the profiles at WQ1 and WQ2 respectively, the water temperature decreased to 21.2 degrees C (70.2 degrees F) at 30.6 feet and 14.2 feet, the DO concentration decreased to 3.0 mg/L at 40.3 feet and 18.0 feet, and the habitat thickness was 9.7 feet and 3.8 feet, at the time of sampling. The thickness of the layer of water in the water column indicates that oxythermal habitat was present for Cisco. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 13.3 degrees C (55.9 degrees F) and 18.1 degrees C (64.6 degrees F), at WQ1 and WQ2 respectively. TDO3 values cooler than 21.2 degrees C (70.2 degrees F) indicate that oxythermal conditions were suitable for Cisco 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 2024 also indicate suitable oxythermal habitat in all years surveyed, with the least favorable conditions recorded in 2025 when the suitable oxythermal habitat layer was 3.8 feet thick. When inadequate oxythermal habitat is available, Cisco are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Temperature and dissolved oxygen measurements were collected on August 14, 2024 in two locations in Iron Lake: the deepest basin, WQ1, just downstream of curtain falls, and in a deep hole on the west side of the lake, WQ2, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in this lake. During the summer, Cisco require a layer of oxythermal habitat that contains water temperatures below 21.2 degrees C (70.2 degrees F) and dissolved oxygen concentrations above 3.0 mg/L. Based on the profiles at WQ1 and WQ2 respectively, the water temperature decreased to 21.2 degrees C (70.2 degrees F) at 30.6 feet and 14.2 feet, the DO concentration decreased to 3.0 mg/L at 40.3 feet and 18.0 feet, and the habitat thickness was 9.7 feet and 3.8 feet, at the time of sampling. The thickness of the layer of water in the water column indicates that oxythermal habitat was present for Cisco. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 13.3 degrees C (55.9 degrees F) and 18.1 degrees C (64.6 degrees F), at WQ1 and WQ2 respectively. TDO3 values cooler than 21.2 degrees C (70.2 degrees F) indicate that oxythermal conditions were suitable for Cisco 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 2024 also indicate suitable oxythermal habitat in all years surveyed, with the least favorable conditions recorded in 2025 when the suitable oxythermal habitat layer was 3.8 feet thick. When inadequate oxythermal habitat is available, Cisco are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Temperature and dissolved oxygen measurements were collected on August 14, 2024 in two locations in Iron Lake: the deepest basin, WQ1, just downstream of curtain falls, and in a deep hole on the west side of the lake, WQ2, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in this lake. During the summer, Cisco require a layer of oxythermal habitat that contains water temperatures below 21.2 degrees C (70.2 degrees F) and dissolved oxygen concentrations above 3.0 mg/L. Based on the profiles at WQ1 and WQ2 respectively, the water temperature decreased to 21.2 degrees C (70.2 degrees F) at 30.6 feet and 14.2 feet, the DO concentration decreased to 3.0 mg/L at 40.3 feet and 18.0 feet, and the habitat thickness was 9.7 feet and 3.8 feet, at the time of sampling. The thickness of the layer of water in the water column indicates that oxythermal habitat was present for Cisco. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 13.3 degrees C (55.9 degrees F) and 18.1 degrees C (64.6 degrees F), at WQ1 and WQ2 respectively. TDO3 values cooler than 21.2 degrees C (70.2 degrees F) indicate that oxythermal conditions were suitable for Cisco 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 2024 also indicate suitable oxythermal habitat in all years surveyed, with the least favorable conditions recorded in 2025 when the suitable oxythermal habitat layer was 3.8 feet thick. When inadequate oxythermal habitat is available, Cisco are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Based on Minnesota DNR survey data, anglers target Northern Pike, Black Crappie, Walleye, Smallmouth Bass, and Rock Bass in Iron. 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 Iron. Check the DNR LakeFinder page for current access details before you go.

Iron has a maximum depth of 64 feet, per Minnesota DNR data.

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

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