Ossawinnamakee

Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Ossawinnamakee Lake on August 6th, 2025, 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 profile from the deepest basin (maximum sampled depth 62.3 feet), the water temperature decreased below 21.2 degrees C (70.2 degrees F) at 17.4 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 32.8 feet at the time of sampling. The thickness of this layer of water in the water column was 15.4 feet, indicating 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 8.3 degrees C (46.9 degrees F). 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 2023 also indicate suitable oxythermal habitat when the suitable oxythermal habitat layer was 16.4 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 (DO) measurements were collected from the deepest basin in Ossawinnamakee Lake on August 6th, 2025, 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 profile from the deepest basin (maximum sampled depth 62.3 feet), the water temperature decreased below 21.2 degrees C (70.2 degrees F) at 17.4 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 32.8 feet at the time of sampling. The thickness of this layer of water in the water column was 15.4 feet, indicating 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 8.3 degrees C (46.9 degrees F). 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 2023 also indicate suitable oxythermal habitat when the suitable oxythermal habitat layer was 16.4 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 (DO) measurements were collected from the deepest basin in Ossawinnamakee Lake on August 6th, 2025, 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 profile from the deepest basin (maximum sampled depth 62.3 feet), the water temperature decreased below 21.2 degrees C (70.2 degrees F) at 17.4 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 32.8 feet at the time of sampling. The thickness of this layer of water in the water column was 15.4 feet, indicating 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 8.3 degrees C (46.9 degrees F). 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 2023 also indicate suitable oxythermal habitat when the suitable oxythermal habitat layer was 16.4 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 Largemouth Bass, Black Crappie, Northern Pike, Rock Bass, and Walleye in Ossawinnamakee. See the full species list above for catch rates, size structure, and quality scores.

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

Ossawinnamakee has a maximum depth of 63 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Ossawinnamakee is from 2021.

Yes — Ossawinnamakee has confirmed Eurasian watermilfoil and zebra mussel. Clean, drain, and dry your equipment to avoid spreading invasives to other waters.