Three Island Lake
Cass County, Minnesota, near Longville. DNR lake ID 11017700.
Three Island Lake is a 287.9-acre lake in Cass County, Minnesota, near Longville. Its deepest point reaches 13 ft, and about 100% of the lake is shallower than 15 feet. Summer water clarity averages 9.0 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 Three Island 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 | 11017700 |
|---|---|
| County | Cass County, near Longville |
| Surface area | 287.9 acres |
| Maximum depth | 13 ft |
| Share under 15 ft | 100% |
| Water clarity (summer) | 9.0 ft through 2023 |
| Phosphorus (summer) | 14.0 µg/L |
| Algae, chlorophyll-a (summer) | 2.5 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 2023: clarity 9.0 ft, phosphorus 14.0 µg/L, algae (chlorophyll-a) 2.5 µg/L. Using the Carlson trophic state index, Three Island Lake rates as mesotrophic.
Fishing on Three Island Lake
The most recent DNR standard fish survey was in 2022 (4 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 |
|---|---|---|---|
| Northern pike | gill | 20.17 | 2.8 to 10.0 |
| Northern pike | trap | 1.0 | n/a |
| Yellow perch | gill | 4.83 | 2.5 to 23.3 |
| Yellow perch | trap | 0.89 | 0.5 to 5.2 |
| Black crappie | gill | 5.33 | 1.5 to 7.5 |
| Black crappie | trap | 1.44 | 1.9 to 13.0 |
| Bluegill | gill | 16.33 | n/a |
| Bluegill | trap | 14.11 | 3.1 to 24.9 |
| Largemouth bass | gill | 2.5 | 0.9 to 4.3 |
| Largemouth bass | trap | 0.11 | 0.3 to 1.9 |
| Pumpkinseed | gill | 2.67 | n/a |
| Pumpkinseed | trap | 0.56 | 0.8 to 7.2 |
| Hybrid sunfish | gill | 3.5 | n/a |
| Hybrid sunfish | trap | 2.89 | n/a |
Largest fish measured in recent DNR samples: Largemouth bass 17.0 in (2022), Northern pike 27.0 in (2022), Walleye 27.0 in (2006).
Game and panfish documented since 2005: Walleye, Northern pike, Largemouth bass, Black crappie, Bluegill, Yellow perch, Pumpkinseed, Hybrid sunfish.
Fishing regulations
No lake-specific regulation found in Minnesota Rules or the DNR sunfish list. Statewide and zone regulations apply.
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
- Three Island Lake: 1 concrete slab launch ramp, 6 trailer spaces. 5 mile northwest of Longville, off County Road 125, on north shore of Three Island Lake. Directions
DNR water access records (2023). Confirm current conditions with the DNR.
Nearby lakes
- Silver Lake 2.3 mi, Cass County
- Cedar Lake 2.4 mi, Cass County
- Hazel Lake 2.8 mi, Cass County
- Horseshoe Lake 2.9 mi, Cass County
- Carnahan Lake 3.1 mi, Cass County
- Boxell Lake 3.3 mi, Cass County
- Maple Lake 3.4 mi, Cass County
- Wawa Lake 3.5 mi, Cass County
Questions about Three Island Lake
How deep is Three Island Lake?
Three Island Lake reaches a maximum depth of 13 ft according to Minnesota DNR records. About 100% of the lake is shallower than 15 feet.
How big is Three Island Lake?
Three Island Lake covers about 287.9 acres in Cass County, Minnesota.
How clear is Three Island Lake?
Summer water clarity on Three Island Lake averages 9.0 feet (Secchi depth) in MPCA monitoring through 2023. Its trophic state is mesotrophic.
Does Three Island Lake have zebra mussels or other invasive species?
Three Island 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 Three Island Lake?
Minnesota DNR surveys document walleye, northern pike, largemouth bass, black crappie, bluegill, yellow perch, pumpkinseed, hybrid sunfish in Three Island Lake. The most recent standard survey was in 2022.
Where is the public boat access on Three Island Lake?
Three Island Lake has 1 public water access site on DNR record: Three Island Lake.
How is the walleye population on Three Island Lake?
In Minnesota DNR net surveys from 1991 to 2006, walleye numbers on Three Island Lake ran mostly below 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 Three Island Lake?
Homes on Three Island 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 Three Island Lake and nearby lakes, including off-market opportunities when available.
What is it like to live on Three Island Lake?
Small, quiet water suited to paddling and fishing, about 100% shallow shoreline under 15 feet, and summer clarity around 9.0 feet. Conditions vary by property, so walk the frontage and ask us what similar homes have sold for.
Are there special fishing regulations on Three Island Lake?
No lake-specific regulation was found for Three Island Lake in Minnesota Rules or the DNR sunfish list. Statewide and zone regulations apply.
Ask us about Three Island 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 2022), 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.