Big Portage Lake
Cass County, Minnesota, near Backus. DNR lake ID 11030800.
Big Portage Lake is a 902.3-acre lake in Cass County, Minnesota, near Backus. Its deepest point reaches 23 ft, and about 100% of the lake is shallower than 15 feet. Summer water clarity averages 8.3 feet in Minnesota Pollution Control Agency monitoring, which places it in the mesotrophic nutrient class. It is not on the DNR infested waters list as of September 2026. DNR surveys document walleye, northern pike, largemouth bass, black crappie, bluegill, yellow perch.
Buying or selling on Big Portage Lake? Ask us what lakeshore here actually sells for, which stretches of shoreline buyers compete for, and what’s coming up before it’s listed.
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Quick facts
| DNR lake ID | 11030800 |
|---|---|
| County | Cass County, near Backus |
| Surface area | 902.3 acres |
| Maximum depth | 23 ft |
| Share under 15 ft | 100% |
| Water clarity (summer) | 8.3 ft through 2025 |
| Phosphorus (summer) | 19.3 µg/L |
| Algae, chlorophyll-a (summer) | 7.1 µg/L |
| Nutrient class | Mesotrophic |
| Invasive species | Not on DNR infested waters list (Sept 2026) |
| Public water accesses | 1 |
Water quality
Summer averages from Minnesota Pollution Control Agency monitoring through 2025: clarity 8.3 ft, phosphorus 19.3 µg/L, algae (chlorophyll-a) 7.1 µg/L. Using the Carlson trophic state index, Big Portage Lake rates as mesotrophic.
Fishing on Big Portage Lake
The most recent DNR standard fish survey was in 2017 (9 years ago). Catch per net is compared with the DNR’s typical range for lakes of the same type.
| Species | Net | Catch per net | Typical range |
|---|---|---|---|
| Walleye | gill | 3.0 | 1.5 to 5.8 |
| Northern pike | gill | 9.62 | 4.6 to 11.6 |
| Yellow perch | gill | 15.75 | 8.0 to 40.3 |
| Black crappie | gill | 5.5 | 1.0 to 7.3 |
| Bluegill | gill | 10.0 | n/a |
| Largemouth bass | gill | 0.62 | 0.3 to 1.3 |
| Pumpkinseed | gill | 1.0 | n/a |
Walleye catch was within the typical range for similar lakes in that survey.
Largest fish measured in recent DNR samples: Walleye 25.0 in (2017), Northern pike 34.0 in (2017), Largemouth bass 12.0 in (2017).
Game and panfish documented since 2005: Walleye, Northern pike, Largemouth bass, Black crappie, Bluegill, Yellow perch, Pumpkinseed, Hybrid sunfish, Rock bass, Bowfin, White sucker, Yellow bullhead, Brown bullhead, Black bullhead.
Fishing regulations
- Sunfish daily limit 10. Crappie daily limit 5. (DNR Quality Sunfish Initiative)
Regulations change. Confirm with the DNR before fishing.
Invasive species
Not on the Minnesota DNR infested waters list as of September 2026. That means no confirmed listing, not a guarantee the lake is free of invasive species.
Public boat access
- Big Portage Lake: 1 concrete slab launch ramp, 1 dock, 4 trailer spaces. 6 mi NE of Backus, on MN Hwy. 87. Directions
DNR water access records (2023). Confirm current conditions with the DNR.
Nearby lakes
- Rainy Lake 1.7 mi, Cass County
- Deep Portage Lake 1.7 mi, Cass County
- Fawn Lake 1.8 mi, Cass County
- Johnson Lake 1.8 mi, Cass County
- Willard Lake 1.9 mi, Cass County
- Sylvan Lake 2.2 mi, Cass County
- Little Portage Lake 2.2 mi, Cass County
- Five Point Lake 2.2 mi, Cass County
Questions about Big Portage Lake
How deep is Big Portage Lake?
Big Portage Lake reaches a maximum depth of 23 ft according to Minnesota DNR records. About 100% of the lake is shallower than 15 feet.
How big is Big Portage Lake?
Big Portage Lake covers about 902.3 acres in Cass County, Minnesota.
How clear is Big Portage Lake?
Summer water clarity on Big Portage Lake averages 8.3 feet (Secchi depth) in MPCA monitoring through 2025. Its trophic state is mesotrophic.
Does Big Portage Lake have zebra mussels or other invasive species?
Big Portage Lake is not on the Minnesota DNR infested waters list as of September 2026. That means there is no confirmed listing; it is not a guarantee the lake is free of invasive species.
What fish are in Big Portage Lake?
Minnesota DNR surveys document walleye, northern pike, largemouth bass, black crappie, bluegill, yellow perch, pumpkinseed, hybrid sunfish, rock bass, bowfin in Big Portage Lake. The most recent standard survey was in 2017.
Where is the public boat access on Big Portage Lake?
Big Portage Lake has 1 public water access site on DNR record: Big Portage Lake.
How is the walleye population on Big Portage Lake?
In Minnesota DNR net surveys from 1997 to 2017, walleye numbers on Big Portage Lake ran mostly within the typical range for similar lakes. Nets measure how many fish a lake holds, not where they’re biting, so local guides are the best source for current fishing.
Are there lake homes for sale on Big Portage Lake?
Homes on Big Portage Lake come up for sale throughout the year, and some sell before they’re ever publicly advertised. Tell us what you’re looking for and our agents will run a custom search and send you matching homes on Big Portage Lake and nearby lakes, including off-market opportunities when available.
What is it like to live on Big Portage Lake?
A mid-size lake with room for boating and fishing, about 100% shallow shoreline under 15 feet, and summer clarity around 8.3 feet. Conditions vary by property, so walk the frontage and ask us what similar homes have sold for.
Are there special fishing regulations on Big Portage Lake?
Yes. Sunfish daily limit 10. Crappie daily limit 5.
Ask us about Big Portage Lake
Whether you’re buying, selling, or just curious, our team works Cass County lakes every day. Send us a note or call (218) 656-6469.
Sources: Minnesota DNR LakeFinder records, DNR fish surveys (latest 2017), DNR infested waters list (Sept 2026), Minnesota Rules 6264.0400 (April 2026), MPCA monitoring via the Water Quality Portal, DNR water access records (2023), LAGOS-US. Lakewide information from public data; it does not describe any specific property. Verify shoreline, bottom type, and depth at any frontage.