Mann Lake
Vilas County, Wisconsin253 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Mann Lake. Here is what has been measured.
- Eutrophic
- 18 ft max depth
- Public access
Mann Lake in Vilas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 6.8 ft visibility. Phosphorus: 32.9 µg/L. Maximum depth: 18 ft. Surface area: 253 acres.
Wisconsin DNR lists Panfish as common on Mann Lake. DNR survey details →
Mann Lake is a 253-acre productive, nutrient-rich eutrophic lake in Vilas County, Wisconsin with a maximum depth of 18 feet. Overall water quality is declining over recent sampling years. The lake supports 2 documented fish species including Panfish and Northern Pike. Public access is available with 1 public boat landing. Compared to the 102 other monitored lakes in Vilas County, Mann Lake ranks #91 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-23. Methodology: how these readings are compared.
Mann Lake covers about 250 acres in Vilas County. It has one public boat landing. Vrbo is where to look for cabins and lake homes around Mann Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Mann Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyModerate algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Mann Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Mann Lake
These are the measurements Wisconsin DNR publishes for Mann Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 6.8 ft. Phosphorus 32.9 µg/L. TSI 52.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 6.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 32.9µg/L | Fair GoodFairPoor |
| 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. | 52 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Mann Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Mann Lake typically sits around 76°F at the surface in August. Summer average is about 73°F. Usually warmest in Jul (about 76°F) and coldest in Apr (about 46°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (46°F) to its warmest (76°F).
Typical surface water temperature by month, from 14 field readings (2024–2025) via the EPA Water Quality Portal. See the full Mann Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Mann Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (409,261 cells/mL) on November 15, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Wisconsin DNR lists Panfish as common on Mann Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Mann Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1995. 9 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
18 ft
Surface area
253 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
3 sq mi
HydroLAKES / HydroSHEDS
Shoreline
4 mi
HydroLAKES / HydroSHEDS
Elevation
1,631 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Mann LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Mann Lake
Compare lakeside cabins, hotels, and vacation rentals near Mann Lake in Vilas County, Wisconsin — 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 Mann Lake
Prices for Oct 16–18, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Follow Mann Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Mann Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Stable+0.27 µg/L/yr6 years
Nearby Lakes in Vilas County
Frequently asked questions about Mann Lake
Where is Mann Lake?
- Mann Lake is a lake in Vilas County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Mann Lake?
- Mann Lake in Vilas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 6.8 ft visibility. Phosphorus: 32.9 µg/L. Maximum depth: 18 ft. Surface area: 253 acres.
Is Mann Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Mann Lake?
- Mann Lake typically sits around 76°F at the surface in August, from 14 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Mann Lake?
- Mann Lake has a maximum depth of 18 feet. The lake covers 253 acres.
What fish are in Mann Lake?
- Fish species found in Mann Lake include Panfish, Northern Pike. Mann Lake is located in Vilas County, Wisconsin.
What did the DNR fisheries survey find at Mann Lake?
- Wisconsin DNR lists Panfish as common on Mann Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Mann Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Does Mann Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Mann Lake (clouds, ice, or an off-season gap). The most recent reading was high (409,261 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Mann Lake?
- Mann Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mann Lake. Public access is listed as yes.
Can I fish at Mann Lake?
- Mann Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Mann Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Vilas County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Northwoods Wisconsin area
Where to stay at Wisconsin's top lakes, each with its readings
Lakes in the Wisconsin River Watershed, ranked by water quality
Wisconsin's cleanest lakes, ranked on agency measurements
More lakes in Wisconsin
Other Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Where this data comes from
45 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX45 samples · 2020–2025
Analytical methods
- Phosphorus by Colorimetry
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory