Deep Portage Lake

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

Minnesota · Minnesota Department of Natural Resources (DNR) · DOW 11023700

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

• Deep Portage Lake shows no stocking records in Minnesota DNR LakeFinder as of September 2, 2026.
• Maximum depth 105 ft, mean depth 40 ft; surface area 129 acres, 31 littoral acres, 1.8 miles of shoreline, per the DNR lake survey.
• Average water clarity (Secchi depth) 11.7 ft.
• Fish species DNR lists here: black crappie, bluegill, largemouth bass, northern pike, pumpkinseed, rock bass, tullibee (cisco), walleye, yellow bullhead.
• 1 public access on the DNR list.
• Most recent DNR fish survey: August 1, 2024 (targeted survey).
• Cass County, nearest town Pontoria; DNR lake number (DOW) 11023700.

Depth map

Bathymetric contours from the Minnesota DNR lake survey; depths in feet. Simplified for the web; not for navigation.

Public accesses

DNR fish survey, 2024

Temperature and dissolved oxygen profiles were collected in the deepest basin in Deep Portage Lake on August 1, 2024, 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. 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, the water temperature decreased to below 21.2 degrees C (70.2 degrees F) at 16.6 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 35.3 feet at the time of sampling. The thickness of this layer of water in the water column was 18.7 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 7.1 degrees C (44.8 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 this survey. Data collected by the Minnesota Department of Natural Resources in 2017-2023 during the late summer thermal stress period also indicate suitable oxythermal habitat in all years surveyed, with the least favorable conditions recorded in 2017. When inadequate oxythermal habitat is available, Cisco are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Minnesota DNR survey narrative, August 1, 2024.

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