Lake Quannapowitt
Middlesex County, MassachusettsView mapDirections
MassDEP publishes the water-quality measurements for Lake Quannapowitt. Here is what has been measured.
- Impaired · Algal growth
- 42 ft max depth
- Limited data
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Answers come straight from the public measurements and survey records on this page.
Lake Quannapowitt in Middlesex County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Water clarity: 1.3 ft visibility.
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Lake Quannapowitt is a lake in Middlesex County, Massachusetts with an estimated average depth of about 42 feet.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2022-07-19. Grade methodology: LakeQuality methodology.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Lake Quannapowitt is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, habitat alterations, pesticides, turbidity. Check local advisories before you swim.
Whether Lake Quannapowitt is safe to swim in today is a call for the Massachusetts Department of Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Quannapowitt
These are the measurements MassDEP publishes for Lake Quannapowitt, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.3 ft of visibility. TSI 73.
| Metric | Value | EPA condition class |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | Measured, not scored |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~42 ft est. |
| Average Depth | ~12 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Massachusetts has not published bathymetry for Lake Quannapowitt.
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.
Fishing Lake Quannapowitt
EPA Impairment Status
Lake Quannapowitt is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MA93060 · Official waterbody report
Nearby Lakes in Middlesex County
Frequently asked questions about Lake Quannapowitt
Where is Lake Quannapowitt?
- Lake Quannapowitt is a lake in Middlesex County, Massachusetts. Its water-quality measurements are published by MassDEP and shown on this page as reported.
What is the water quality of Lake Quannapowitt?
- Lake Quannapowitt in Middlesex County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Water clarity: 1.3 ft visibility.
Is Lake Quannapowitt safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Quannapowitt is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, habitat alterations, pesticides, turbidity. Check local advisories before you swim.
How deep is Lake Quannapowitt?
- No published bathymetric survey covers Lake Quannapowitt, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 42 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
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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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)