Twin Lake
Twin Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.6 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 2.5 µg/L.
- Clarity
- 3.6 ft
Next lake in St. Louis County
Why Twin 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 Twin Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, 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.
Twin Lake is a lake in St. Louis County, Minnesota.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-09-15. 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 Twin Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 3.6 ft. Phosphorus level: 13 µg/L. Chlorophyll-a: 2.5 µg/L. Trophic State Index: 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.6 ft | Not graded |
| Phosphorus | 13 µg/L | Not graded |
| Chlorophyll-a (Algae) | 2.5 µg/L | Not graded |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Twin Lake
Compare lakeside cabins, hotels, and vacation rentals near Twin Lake in St. Louis 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 Twin Lake
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Fishing Twin Lake
Graded lakes near Twin Lake
Twin Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in St. Louis County
Frequently asked questions about Twin Lake
What is the water quality grade for Twin Lake?
- Twin Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.6 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 2.5 µg/L.
Is Twin Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Twin Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 2.5 µg/L. Always check local health department advisories before swimming.
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Where this data comes from
5 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA5 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- 2120 B ~ Color in Water by Visual Comparison
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.