Mary Lake
Mary Lake in Marinette County, Wisconsin has a water quality grade of B (Good). Water clarity: 9 ft visibility. Phosphorus: 13.5 µg/L. Maximum depth: 38 ft. Surface area: 186 acres.
- Clarity
- 9 ft
- Max depth
- 38 ft
- Area
- 186 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
Next lake in Marinette County
Mary Lake is a 186-acre mesotrophic lake in Marinette County, Wisconsin with a maximum depth of 38 feet. Water quality is graded B based on 1 sampling years through 2023. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 3 public boat landings. Compared to the 9 other monitored lakes in Marinette County, Mary Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2023-08-28. Grade methodology: LakeGrade methodology.
Watch Mary Lake water quality
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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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Moderate clarity, visible to about 9 ft. Phosphorus level: 13.5 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9 ft | Not graded |
| Phosphorus | 13.5 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Mary Lake
Compare lakeside cabins, hotels, and vacation rentals near Mary Lake in Marinette 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.
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 38 ft |
| Surface Area | 186 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lake Mary (East)Public
- Lake Mary (West)Public
- Bear PointPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Mary 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.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 2 stations on file (most recent sample 2023).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Mary Lake covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2020Timms Lake fishery summary, 2020Fisheries Survey · WI DNR · 2020 (PDF)
Water Quality Trend: → Stable
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.075 m/yr | 4 |
| Phosphorus | → Stable | +0.23 µg/L/yr | 4 |
County Ranking
Ranked #5 of 10 lakes in Marinette County
Nearby Lakes in Marinette County
Frequently asked questions about Mary Lake
What is the water quality grade for Mary Lake?
- Mary Lake in Marinette County, Wisconsin has a water quality grade of B (Good). Water clarity: 9 ft visibility. Phosphorus: 13.5 µg/L. Maximum depth: 38 ft. Surface area: 186 acres.
Is Mary Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Mary Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Mary Lake?
- Mary Lake has a maximum depth of 38 feet. The lake covers 186 acres.
What fish are in Mary Lake?
- Fish species found in Mary Lake include Panfish, Largemouth Bass, Northern Pike. Mary Lake is located in Marinette County, Wisconsin.
Are there boat ramps on Mary Lake?
- Mary Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lake Mary (East), Lake Mary (West), Bear Point. Public access is listed as yes.
Explore Mary Lake across LakeGrade
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Fish species and best lakes in Marinette County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its grade
Moderate nutrients, good water quality
Wisconsin's cleanest and most-polluted lakes, ranked
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State Parks Near Mary Lake
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
46 measurements from 2 monitoring stations, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX46 samples · 2020–2023
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (2)
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
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