Lake Groton is a mesotrophic lake in Caledonia County, Vermont. Water quality is graded A based on 3 sampling years through 2025. Compared to the 22 other monitored lakes in Caledonia County, Lake Groton ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, Vermont DNR, last sampled 2025-08-21. Grade methodology: LakeGrade methodology.
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 13.1 ft. Phosphorus level: 11.3 µg/L. Chlorophyll-a: 3.3 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.1 ft | B |
| Phosphorus | 11.3 µg/L | A |
| Chlorophyll-a (Algae) | 3.3 µg/L | A |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lake Groton
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Fishing Lake Groton
Location
County Ranking
Ranked #8 of 23 lakes in Caledonia County
Nearby Lakes in Caledonia County
Explore Lake Groton across LakeGrade
More Vermont Lake Rankings
Other Grade A Lakes in Vermont
Mesotrophic Lakes in Vermont
More records, surveys & data sources
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-08-21
Monitoring stations: 1