Middlesex County, Massachusetts · Water Quality Report Card
Lake Quannapowitt
Lake Quannapowitt in Middlesex County, Massachusetts is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.3 ft visibility.
- Clarity
- 1.3 ft
- Mean depth
- ~12 ft est.
- Type
- Hypereutrophic
Lake Quannapowitt is a highly nutrient-loaded hypereutrophic lake in Middlesex County, Massachusetts with an estimated average depth of about 12 feet.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2022-07-19. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not rated for swimming — there is not enough monitoring data to judge this lake
Water Quality Grade: Not rated
Very murky, less than 1.3 ft of visibility. Trophic State Index: 73.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~12 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Massachusetts has not published bathymetry for Lake Quannapowitt.
Where to stay near Lake Quannapowitt
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Fishing Lake Quannapowitt
Location
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More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Where this data comes from
1 measurement from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS1 sample · 2022
Monitoring station identifiers (1)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2022-07-19
Monitoring stations: 1