Mary Lake
Mary Lake in Watonwan County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 122 acres.
- Area
- 122 acres
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Why Mary Lake has no grade
We grade a lake only when the monitoring record supports a letter: 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, no water-quality sampling on record for this lake.
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 122-acre lake in Watonwan County, Minnesota.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled recent years. Grade methodology: LakeQuality methodology.
Watch Mary Lake water quality
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Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Mary Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay near Mary Lake
Compare lakeside cabins, hotels, and vacation rentals near Mary Lake in Watonwan 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 |
|---|---|
| Surface Area | 122 acres |
No bathymetric survey has been published for Mary Lake, so its depth is not documented here.
Fishing Mary Lake
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Frequently asked questions about Mary Lake
Where is Mary Lake?
- Mary Lake is a lake in Watonwan County, Minnesota. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for Mary Lake?
- Mary Lake in Watonwan County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 122 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.
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Where this data comes from
Measurements for Mary Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Lake details from Minnesota DNR LakeFinder