Mary Lake
Mary Lake in Itasca County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Maximum depth: 45 ft. Surface area: 211.76 acres.
- Clarity
- 10.5 ft
- Max depth
- 45 ft
- Area
- 212 acres
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- May 1
Next lake in Itasca County
Why Mary Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Mary Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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 with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-10-23. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Mary Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Good clarity, visible to about 10.5 ft. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Mary Lake
Compare lakeside cabins, hotels, and vacation rentals near Mary Lake in Itasca 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.
Top-rated places to stay near Mary Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 45 ft |
| Surface Area | 212 acres |
| Shoreline Length | 4.4 mi |
| Littoral Zone | 45% |
| Public Access | Yes |
Recreation & Access
- Eagle LakePublic
Fishing Mary Lake
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 1987-06-15 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | 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, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
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
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.31 m/yr | 2 |
Ice Season
Historical ice data from Minnesota DNR (6 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2020-04-26 (2020) | 2022-05-08 (2022) |
| Ice-In | 2017-11-07 (2017) | 2018-11-11 (2018) |
Most recent ice-out: 2022-05-08
Graded lakes near Mary Lake
Mary Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Itasca County
Frequently asked questions about Mary Lake
What is the water quality grade for Mary Lake?
- Mary Lake in Itasca County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Maximum depth: 45 ft. Surface area: 211.76 acres.
Is Mary Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Mary Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Mary Lake?
- Mary Lake has a maximum depth of 45 feet. The lake covers 211.76 acres.
When does Mary Lake thaw?
- Mary Lake typically has ice-out around May 1.
Are there boat ramps on Mary Lake?
- Mary Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Eagle Lake. Public access is listed as yes.
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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)
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 details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate