Thelma Lake
Thelma Lake in Cook County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 67 acres.
- Area
- 67 acres
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Why Thelma 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 Thelma 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.
Thelma Lake is a 67-acre lake in Cook County, Minnesota.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled recent years. Grade methodology: LakeQuality methodology.
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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 Thelma 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 Thelma Lake
Compare lakeside cabins, hotels, and vacation rentals near Thelma Lake in Cook 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 Thelma Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 67 acres |
No bathymetric survey has been published for Thelma Lake, so its depth is not documented here.
Fishing Thelma Lake
Nearby Lakes in Cook County
Frequently asked questions about Thelma Lake
Where is Thelma Lake?
- Thelma Lake is a lake in Cook 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 Thelma Lake?
- Thelma Lake in Cook County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 67 acres.
Is Thelma Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Thelma 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 Thelma 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