Man Lake
Man Lake in Cass County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Maximum depth: 93 ft. Surface area: 491.05 acres.
- Clarity
- 11 ft
- Typical in August
- 73°F
- Max depth
- 93 ft
- Area
- 491 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- No
- Ice-out
- Apr 23
- Open water
- 229 days
Next lake in Cass County
Man Lake is a 491-acre mesotrophic lake in Cass County, Minnesota with a maximum depth of 93 feet. Water quality is graded A based on 2 sampling years through 2025. Water clarity is improving over recent sampling years. The lake supports 14 documented fish species including black crappie, bluegill, and hybrid sunfish. No public access — the lake is private or restricted. Compared to the 103 other monitored lakes in Cass County, Man Lake ranks #35 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11 ft. Phosphorus level: 10 µg/L. Chlorophyll-a: 2.7 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11 ft | Not graded |
| Phosphorus | 10 µg/L | Good |
| Chlorophyll-a (Algae) | 2.7 µg/L | Good |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Man Lake
Compare lakeside cabins, hotels, and vacation rentals near Man 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.
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Water Temperature
Man Lake typically sits around 73°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 77°F) and coldest in Jun (about 65°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 37 field readings (2011–2025) via the EPA Water Quality Portal. See the full Man Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 93 ft |
| Surface Area | 491 acres |
| Shoreline Length | 4.5 mi |
| Littoral Zone | 9% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Man Lake
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2022-07-05 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| CSH | 20.62 | 0.09 lb |
| Smallmouth Bass | 13.45 | 1.04 lb |
| Bluegill | 13.32 | 0.14 lb |
| MMS | 11.39 | — |
| Tullibee (Cisco) | 8.98 | 0.23 lb |
| Largemouth Bass | 6.84 | 0.76 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
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.
CSH
Smallmouth Bass
Bluegill
Tullibee (Cisco)
From the 2022-07-05 survey
A targeted survey of nearshore fish species in Man Lake was conducted on July 5-7, 2022, by DNR Index of Biological Integrity (IBI) Program staff. Sampling sites were evenly spaced around the lake, and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible. Backpack…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Man Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — ManFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Man (1598)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — ManFish Stocking History · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.096 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.24 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | +0.03 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (15 observations).
Estimated open water season: 229 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2006-04-12 (2006) | 1996-05-08 (1996) |
| Ice-In | 2000-11-28 (2000) | 1998-12-20 (1998) |
Most recent ice-out: 2008-05-07
EPA Impairment Status
Man Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN11-0283-00 · Official waterbody report · Matched by proximity (1.75 km)
County Ranking
Ranked #35 of 104 lakes in Cass County
Nearby Lakes in Cass County
Frequently asked questions about Man Lake
What is the water quality grade for Man Lake?
- Man Lake in Cass County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Maximum depth: 93 ft. Surface area: 491.05 acres.
Is Man Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Man Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.7 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Man Lake?
- Man Lake typically sits around 73°F at the surface in August, from 37 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Man Lake?
- Man Lake has a maximum depth of 93 feet. The lake covers 491.05 acres.
What fish are in Man Lake?
- Fish species found in Man Lake include black crappie, bluegill, hybrid sunfish, largemouth bass, muskellunge, northern pike, pumpkinseed, rock bass, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Man Lake is located in Cass County, Minnesota.
When does Man Lake thaw?
- Man Lake typically has ice-out around Apr 23. Ice typically forms around Dec 8. The open water season is approximately 229 days.
Explore Man Lake across LakeGrade
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Species activity outlook by water temperature and season
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Where to stay at Minnesota's top lakes, each with its grade
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Moderate nutrients, good water quality
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Where this data comes from
122 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
MNPCA122 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated 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