Portage Lake
Cass County, Minnesota277 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Portage Lake. Here is what has been measured.
- Impaired · Mercury
- 84 ft max depth
- Limited data
Portage Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 21 ft visibility. Maximum depth: 84 ft. Surface area: 277.27 acres.
Minnesota DNR's Standard Survey on July 7, 2025 caught 1.83 walleye per gill net at Portage Lake. DNR survey details →
Portage Lake is a 277-acre lake in Cass County, Minnesota with a maximum depth of 84 feet. The lake supports 10 documented fish species including black crappie, bluegill, and hybrid sunfish. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-12. Methodology: how these readings are compared.
What Portage Lake is good for
From access and monitoring records, not editorial picks.
- Clear water21 ft of visibility
- Fishing10 species recorded
- Ice seasonIce-out around Apr 27
- Deep water84 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Portage Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. 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.
Crystal clear, you can see 21 ft down. TSI 33.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 21ft | 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. | 33 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
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 (21,281 cells/mL) on June 6, 2026.
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 July 7, 2025 caught 1.83 walleye per gill net at Portage Lake.
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 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2025-07-07 (Standard Survey).
13 surveys on file · most recent 2025-07-07 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluntnose Minnow | 32.39 | ||
| Largemouth Bass | 18.00 | 5–11 in 2025-07-07 | 0.85 lb |
| Bluegill | 15.43 | 2–8 in 2025-07-07 | 0.11 lb |
| Smallmouth Bass | 6.07 | 4–16 in 2025-07-07 | 1.09 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.
Largemouth Bass
Bluegill
Smallmouth Bass
From the 2025-07-07 survey
Portage Lake (DOW# 11-0476; Lake Class 23) is a 277-acre lake with 95 littoral acres, 3.1 miles of shoreline and a maximum depth of 84 feet located near Hackensack, MN. A US Forest Service owned public access is located on the south shore. The Minnesota Department of Natural Resources has classified Minnesota's lakes…
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 (1460)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — PortageFish Stocking History · MN DNR LakeFinder
Lake Details
Max depth
84 ft
Surface area
277 acres
Shoreline
3.1 mi
Littoral zone
34%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
3 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,371 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.
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Fish Species
Click a species to see every lake where it is documented.
Fishing Portage Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Ice season
Typical ice-out
Apr 27
Earliest Apr 21, 2007 · Latest May 19, 2004
Typical ice-in
Nov 30
Earliest Nov 24, 2002 · Latest Dec 14, 2004
Most recent ice-out
Apr 26
2020
12 observations · Minnesota PCA ice records
EPA Impairment Status
Portage Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit MN11-0476-00 · Official waterbody report
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: 21 ft visibility. Maximum depth: 84 ft. Surface area: 277.27 acres.
Is Portage Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Portage Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
How deep is Portage Lake?
- Portage Lake has a maximum depth of 84 feet. The lake covers 277.27 acres.
What fish are in Portage Lake?
- Fish species found in Portage Lake include black crappie, bluegill, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, smallmouth bass, 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 July 7, 2025 caught 1.83 walleye per gill net at Portage Lake. 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 6 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 27. Ice typically forms around Nov 30. The open water season is approximately 217 days.
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 (21,281 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 no on the lake record, so confirm before you make the trip. 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.
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Where this data comes from
33 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA33 samples · 2020–2025
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate