Wachusett Lake
Worcester County, Massachusetts130 acresView mapDirections
MassDEP publishes the water-quality measurements for Wachusett Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- 47 ft max depth
- Limited data
Wachusett Lake in Worcester County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 130 acres.
Wachusett Lake is a 130-acre mesotrophic lake in Worcester County, Massachusetts with an estimated average depth of about 47 feet. Compared to the 23 other monitored lakes in Worcester County, Wachusett Lake ranks #10 for water quality.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2017-09-19. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Wachusett Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether Wachusett Lake 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 Wachusett Lake
These are the measurements MassDEP publishes for Wachusett Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Chlorophyll-a 2.4 µg/L. TSI 39.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | 2.4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 39 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Wachusett Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~47 ft est.
Surface area
130 acres
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Massachusetts has not published bathymetry for Wachusett Lake.
Lake Size & Watershed
Watershed (drainage) area
8 sq mi
HydroLAKES / HydroSHEDS
Shoreline
9.2 mi
HydroLAKES / HydroSHEDS
Elevation
899 ft
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.
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Fishing Wachusett Lake
Reservoir Info (USACE NID)
Wachusett Lake is a man-made reservoir impounded by the Wachusett Lake Dam (completed 1905), built primarily for flood risk reduction on the Tributary to North Nashua River; earth-type dam, 4 ft tall and 400 ft long.
- Surface area
- 130 ac
- Normal storage
- 187 ac-ft
- Max storage
- 579 ac-ft
- Drainage area
- 1.52 sq mi
- Hazard class
- Significant
- Owner
- City of Fitchburg
Source: USACE National Inventory of Dams, NID ID MA00642 · Operator website
EPA Impairment Status
Wachusett Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit MA81146 · Official waterbody report
Nearby Lakes in Worcester County
Frequently asked questions about Wachusett Lake
Where is Wachusett Lake?
- Wachusett Lake is a lake in Worcester County, Massachusetts. Its water-quality measurements are published by MassDEP and shown on this page as reported.
What is the water quality of Wachusett Lake?
- Wachusett Lake in Worcester County, Massachusetts has water-quality measurements published by MassDEP, shown here as reported. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 130 acres.
Is Wachusett Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Wachusett Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
How deep is Wachusett Lake?
- No published bathymetric survey covers Wachusett Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 47 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 130 acres.
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Where this data comes from
3 measurements from 1 monitoring station, 2017. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Massachusetts Department of Environmental Protection (MassDEP)
MASSDEP3 samples · 2017
Analytical methods
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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)