Portage Lake
Cass County, Minnesota361 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Portage Lake. Here is what has been measured.
- 65 ft max depth
- Public access
- Limited data
Portage Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 12 ft visibility. Maximum depth: 65 ft. Surface area: 360.65 acres.
Minnesota DNR's Standard Survey on August 18, 1998 caught 3.89 walleye per gill net at Portage Lake. Length samples in the latest survey that recorded them ran 6–25 inches. DNR survey details →
Portage Lake is a 361-acre lake in Cass County, Minnesota with a maximum depth of 65 feet. The lake supports 13 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-09-21. Methodology: how these readings are compared.
What Portage Lake is good for
From access and monitoring records, not editorial picks.
- Clear water12 ft of visibility
- Fishing13 species recorded
- Ice seasonIce-out around Apr 20
- Deep water65 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Portage Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Portage Lake
These are the measurements Minnesota PCA publishes for Portage Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 12 ft. TSI 41.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 12ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 41 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Portage Lake
Answers come straight from the public measurements and survey records on this page.
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Portage Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (23,768 cells/mL) on November 22, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR's Standard Survey on August 18, 1998 caught 3.89 walleye per gill net at Portage Lake. Length samples in the latest survey that recorded them ran 6–25 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Portage Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
6 surveys on file from MN DNR Fisheries. Most recent: 1998-08-18 (Standard Survey).
6 surveys on file · most recent 1998-08-18 (Standard Survey)
28 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Yellow Perch | 35.22 | 1–9 in 1998-08-18 | 0.15 lb |
| Pumpkinseed | 5.77 | 3–6 in 1998-08-18 | 0.23 lb |
| Bluegill | 4.13 | 2–9 in 1998-08-18 | 0.41 lb |
| Northern Pike | 3.88 | 14–36 in 1998-08-18 | 1.7 lb |
| Tullibee (Cisco) | 3.39 | 7–18 in 1998-08-18 | 1.28 lb |
| Walleye | 3.18 | 6–25 in 1998-08-18 | 1.94 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Yellow Perch
Pumpkinseed
Bluegill
Northern Pike
From the 1998-08-18 survey
Portage Lake is a 356-acre lake with a maximum depth of 65 feet. The lake is located six miles south of Cass Lake in northern Cass County. The Minnesota Department of Natural Resources has classified Minnesota's lakes into 43 different lake classes based on physical and chemical characteristics. Portage Lake is in…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Portage Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — PortageFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Portage (1631)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — PortageFish Stocking History · MN DNR LakeFinder
Lake Details
Max depth
65 ft
Surface area
361 acres
Shoreline
3.6 mi
Littoral zone
47%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,289 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Portage Lake
Compare lakeside cabins, hotels, and vacation rentals near Portage Lake in Cass County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Portage Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Follow Portage Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fish Species
Click a species to see every lake where it is documented.
Fishing Portage Lake
Water quality readings over time
2 seasons of samples on record (2020–2021). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Stable2 years
Ice season
Typical ice-out
Apr 20
Earliest Apr 12, 2015 · Latest Apr 21, 2008
Most recent ice-out
Apr 12
2015
5 observations · Minnesota PCA ice records
Nearby Lakes in Cass County
Frequently asked questions about Portage Lake
Where is Portage Lake?
- Portage Lake is a lake in Cass County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Portage Lake?
- Portage Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 12 ft visibility. Maximum depth: 65 ft. Surface area: 360.65 acres.
Is Portage Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Portage Lake?
- Portage Lake has a maximum depth of 65 feet. The lake covers 360.65 acres.
What fish are in Portage Lake?
- Fish species found in Portage Lake include black crappie, bluegill, bowfin (dogfish), hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow perch. Portage Lake is located in Cass County, Minnesota.
What did the DNR fisheries survey find at Portage Lake?
- Minnesota DNR's Standard Survey on August 18, 1998 caught 3.89 walleye per gill net at Portage Lake. Length samples in the latest survey that recorded them ran 6–25 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Portage Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
When does Portage Lake thaw?
- Portage Lake typically has ice-out around Apr 20.
Does Portage Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Portage Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (23,768 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Can I fish at Portage Lake?
- Public access to Portage Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Portage Lake across LakeQuality
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Cass County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Brainerd Lakes area
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Mississippi Headwaters, ranked by water quality
Lakes in the Pine River Watersheds (Brainerd Lakes), ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
More lakes in Minnesota
State Parks Near Portage Lake
Other Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Where this data comes from
10 measurements from 1 monitoring station, 2020–2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA10 samples · 2020–2021
Analytical methods
- Field measurement/observation, generic method
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate