Worcester County, Massachusetts · Water Quality Report Card
Wachusett Reservoir
Wachusett Reservoir in Worcester County, Massachusetts is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 25.8 ft visibility.
- Clarity
- 25.8 ft
- Mean depth
- ~56 ft est.
- Type
- Oligotrophic
- Trend
- ↓ Declining
Wachusett Reservoir is a cold, clear oligotrophic lake in Worcester County, Massachusetts with an estimated average depth of about 56 feet. Overall water quality is declining over recent sampling years.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2023-07-31. 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
Crystal clear, you can see 25.8 ft down. Trophic State Index: 30.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 25.8 ft | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 30 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~56 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Massachusetts has not published bathymetry for Wachusett Reservoir.
Where to stay near Wachusett Reservoir
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Fishing Wachusett Reservoir
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -2.16 m/yr | 2 |
Location
Nearby Lakes in Worcester County
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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
20 measurements from 1 monitoring station, 2022–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS20 samples · 2022–2023
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: 2023-07-31
Monitoring stations: 1