Mary Lake
Lincoln County, Wisconsin25 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Mary Lake. Here is what has been measured.
- 42 ft max depth
- Limited data
Mary Lake in Lincoln County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 21 ft visibility. Maximum depth: 42 ft. Surface area: 25 acres.
Wisconsin DNR lists Largemouth Bass as present on Mary Lake. DNR survey details →
Mary Lake is a 25-acre lake in Lincoln County, Wisconsin with a maximum depth of 42 feet. Overall water quality is improving over recent sampling years. The lake supports 1 documented fish species including Largemouth Bass.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2023-07-24. Methodology: how these readings are compared.
What Mary Lake is good for
From access and monitoring records, not editorial picks.
- Clear water21 ft of visibility
- Deep water42 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Mary 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 Mary Lake
These are the measurements Wisconsin DNR publishes for Mary Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 21 ft down. TSI 33.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 21ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| 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. | 33 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Mary Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR lists Largemouth Bass as present on Mary Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Mary Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. 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. 1 station 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).
- 2025Pine Lake spring summary report, 2025Fisheries Survey · WI DNR · 2025 (PDF)
Lake Details
Max depth
42 ft
Surface area
25 acres
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Stays near Mary Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Mary Lake
Water Quality Trend: Improving
Based on 7 years of monitoring (2020–2026).
Water clarity
Improving6 years
Phosphorus
Improving-1.58 µg/L/yr7 years
Nearby Lakes in Lincoln County
Frequently asked questions about Mary Lake
Where is Mary Lake?
- Mary Lake is a lake in Lincoln County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Mary Lake?
- Mary Lake in Lincoln County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 21 ft visibility. Maximum depth: 42 ft. Surface area: 25 acres.
Is Mary Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Mary Lake?
- Mary Lake has a maximum depth of 42 feet. The lake covers 25 acres.
What fish are in Mary Lake?
- Fish species found in Mary Lake include Largemouth Bass. Mary Lake is located in Lincoln County, Wisconsin.
What did the DNR fisheries survey find at Mary Lake?
- Wisconsin DNR lists Largemouth Bass as present on Mary Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Mary Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
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Where this data comes from
2 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX2 samples · 2023
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
Fish and recreation data from Wisconsin DNR Lakes