Cooper Lake
Cass County, Minnesota, near Longville. DNR lake ID 11016300.
Cooper Lake is a 132.5-acre lake in Cass County, Minnesota, near Longville. Its deepest point reaches 70 ft, and about 73% of the lake is shallower than 15 feet. Summer water clarity averages 16.6 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.
Buying or selling on Cooper 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 | 11016300 |
|---|---|
| County | Cass County, near Longville |
| Surface area | 132.5 acres |
| Maximum depth | 70 ft |
| Share under 15 ft | 73% |
| Water clarity (summer) | 16.6 ft through 2025 |
| Phosphorus (summer) | 16.9 µg/L |
| Algae, chlorophyll-a (summer) | 3.2 µg/L |
| Nutrient class | Mesotrophic |
| Clarity trend | Steady (2016 to 2025) |
| Invasive species | Not on DNR infested waters list (Sept 2026) |
| Public water accesses | 0 |
Water quality
Summer averages from Minnesota Pollution Control Agency monitoring through 2025: clarity 16.6 ft, phosphorus 16.9 µg/L, algae (chlorophyll-a) 3.2 µg/L. Using the Carlson trophic state index, Cooper Lake rates as mesotrophic. Summer clarity trend 2016 to 2025: steady.
Fishing on Cooper Lake
The most recent DNR standard fish survey was in 1987 (39 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 | 0.33 | 0.5 to 2.3 |
| Northern pike | gill | 5.33 | 3.5 to 8.9 |
| Yellow perch | gill | 8.33 | 1.0 to 10.3 |
| Yellow perch | trap | 1.67 | 0.3 to 1.2 |
| Bluegill | gill | 12.67 | n/a |
| Bluegill | trap | 40.0 | 9.5 to 57.3 |
| Largemouth bass | gill | 1.33 | 0.4 to 1.6 |
| Largemouth bass | trap | 1.0 | 0.3 to 1.4 |
| Tullibee (cisco) | gill | 10.0 | 2.3 to 10.0 |
| Pumpkinseed | gill | 10.0 | n/a |
| Pumpkinseed | trap | 10.67 | 1.5 to 6.8 |
| Rock bass | gill | 3.0 | 0.5 to 1.7 |
| Rock bass | trap | 2.0 | 0.4 to 1.7 |
| Hybrid sunfish | trap | 1.0 | n/a |
Walleye catch was below the typical range for similar lakes in that survey.
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
No public water access on DNR record.
Nearby lakes
- Shurd Lake 0.8 mi, Cass County
- Rice Lake 1.5 mi, Cass County
- Little Boy Lake 1.7 mi, Cass County
- Girl Lake 2.0 mi, Cass County
- Boxell Lake 3.0 mi, Cass County
- Hunter Lake 3.1 mi, Cass County
- Inguadona Lake 3.1 mi, Cass County
- Broadwater Bay 3.3 mi, Cass County
Questions about Cooper Lake
How deep is Cooper Lake?
Cooper Lake reaches a maximum depth of 70 ft according to Minnesota DNR records. About 73% of the lake is shallower than 15 feet.
How big is Cooper Lake?
Cooper Lake covers about 132.5 acres in Cass County, Minnesota.
How clear is Cooper Lake?
Summer water clarity on Cooper Lake averages 16.6 feet (Secchi depth) in MPCA monitoring through 2025. Its trophic state is mesotrophic.
Does Cooper Lake have zebra mussels or other invasive species?
Cooper 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.
Are there lake homes for sale on Cooper Lake?
Homes on Cooper 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 Cooper Lake and nearby lakes, including off-market opportunities when available.
What is it like to live on Cooper Lake?
Small, quiet water suited to paddling and fishing, about 73% shallow shoreline under 15 feet, and summer clarity around 16.6 feet. Conditions vary by property, so walk the frontage and ask us what similar homes have sold for.
Are there special fishing regulations on Cooper Lake?
No lake-specific regulation was found for Cooper Lake in Minnesota Rules or the DNR sunfish list. Statewide and zone regulations apply.
Ask us about Cooper 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 1987), 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.