Mary Lake
Itasca County, Minnesota212 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Mary Lake. Here is what has been measured.
- 45 ft max depth
- Public access
- Limited data
Mary Lake in Itasca County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 10.5 ft visibility. Maximum depth: 45 ft. Surface area: 211.76 acres.
Minnesota DNR's Standard Survey on June 15, 1987 caught 13.20 northern pike per gill net at Mary Lake. DNR survey details →
Mary Lake is a 212-acre lake in Itasca County, Minnesota with a maximum depth of 45 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-10-23. Methodology: how these readings are compared.
What Mary Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.5 ft of visibility
- Ice seasonIce-out around May 1
- Deep water45 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 Minnesota Pollution Control Agency and the Minnesota DNR 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 Minnesota PCA 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.
Good clarity, visible to about 10.5 ft. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.5ft | 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. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Mary Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on June 15, 1987 caught 13.20 northern pike per gill net at 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 2 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 1987-06-15 (Standard Survey).
2 surveys on file · most recent 1987-06-15 (Standard Survey)
39 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 12.60 | 0.19 lb | |
| Northern Pike | 6.42 | 1.75 lb | |
| Yellow Perch | 2.50 | 0.12 lb | |
| Black Crappie | 2.49 | 0.39 lb | |
| Pumpkinseed | 1.67 | 0.18 lb | |
| Rock Bass | 1.30 | 0.52 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
From the 1987-06-15 survey
NET CATCHES INDICATE THAT NORTHERN PIKE POPULATION ABOVE STATE AND LOCAL MEDIANS. BLUEGILLS ARE ABUN- DANT, BUT SMALL. OTHER SPECIES AT LEVELS COMPAR- ABLE TO OTHER LAKES OF THIS TYPE.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Mary Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — MaryFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Max depth
45 ft
Surface area
212 acres
Shoreline
4.4 mi
Littoral zone
45%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
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Stays near Mary Lake
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Fishing Mary Lake
Water quality readings over time
2 seasons of samples on record (2020–2021). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Ice season
Typical ice-out
May 1
Earliest Apr 26, 2020 · Latest May 8, 2022
Most recent ice-out
May 8
2022
6 observations · Minnesota PCA ice records
Nearby Lakes in Itasca County
Frequently asked questions about Mary Lake
Where is Mary Lake?
- Mary Lake is a lake in Itasca County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Mary Lake?
- Mary Lake in Itasca County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 10.5 ft visibility. Maximum depth: 45 ft. Surface area: 211.76 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 45 feet. The lake covers 211.76 acres.
What did the DNR fisheries survey find at Mary Lake?
- Minnesota DNR's Standard Survey on June 15, 1987 caught 13.20 northern pike per gill net at 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 2 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
When does Mary Lake thaw?
- Mary Lake typically has ice-out around May 1.
Can I fish at Mary Lake?
- Public access to Mary Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
23 measurements from 1 monitoring station, 2020–2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA23 samples · 2020–2021
Analytical methods
- Field measurement/observation, generic method
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 details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate