East Brimfield Reservoir
Worcester County, Massachusetts360 acresView mapDirections
Nutrients and algae sit mid-range for this region.
- Mesotrophic
- Impaired · Mercury
- #18 of 24 in the county
- 49 ft max depth
- Public access
- Limited data
East Brimfield Reservoir in Worcester County, Massachusetts has a water quality grade of C (Fair). Chlorophyll-a (algae): 5.9 µg/L. Surface area: 360 acres.
- Max depth
- ~49 ft est.
- Area
- 360 acres
- Type
- Mesotrophic
- Chlorophyll-a
- 5.9 µg/L
- Public access
- Yes
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Watch East Brimfield Reservoir’s letter
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East Brimfield Reservoir is a 360-acre mesotrophic lake in Worcester County, Massachusetts with an estimated average depth of about 49 feet. Water quality is graded C based on 1 sampling years through 2016. Limited fish-species data available. Public access is available. Compared to the 23 other monitored lakes in Worcester County, East Brimfield Reservoir ranks #18 for water quality.
Source: EPA Water Quality Portal sampling records, MassDEP, last sampled 2016-09-08. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The C is nutrients and algae, not a swimming clearance. East Brimfield Reservoir is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nuisance exotic species. Check local advisories before you swim.
Water Quality Grade: C (Fair)
No clarity data. Chlorophyll-a 5.9 µg/L. TSI 48. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 5.9 µg/L | Fair |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~49 ft est. |
| Average Depth | ~25 ft est. |
| Surface Area | 360 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Massachusetts has not published bathymetry for East Brimfield Reservoir.
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 East Brimfield Reservoir
Reservoir Info (USACE NID)
East Brimfield Reservoir is a man-made reservoir impounded by the East Brimfield Dam (completed 1960), built primarily for flood risk reduction on the Quinebaug River; rockfill-type dam, 53 ft tall and 520 ft long.
- Surface area
- 360 ac
- Normal storage
- 1,200 ac-ft
- Max storage
- 71,000 ac-ft
- Drainage area
- 68 sq mi
- Hazard class
- High
- Owner
- USACE - New England District
All listed purposes: Flood Risk Reduction;Recreation.
Source: USACE National Inventory of Dams, NID ID MA00966 · Operator website
EPA Impairment Status
East Brimfield Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MA41014 · Official waterbody report
County Ranking
Ranked #18 of 24 lakes in Worcester County
Nearby Lakes in Worcester County
Frequently asked questions about East Brimfield Reservoir
Where is East Brimfield Reservoir?
- East Brimfield Reservoir is a lake in Worcester County, Massachusetts. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for East Brimfield Reservoir?
- East Brimfield Reservoir in Worcester County, Massachusetts has a water quality grade of C (Fair). Chlorophyll-a (algae): 5.9 µg/L. Surface area: 360 acres.
Is East Brimfield Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. East Brimfield Reservoir is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nuisance exotic species. Check local advisories before you swim.
How deep is East Brimfield Reservoir?
- No published bathymetric survey covers East Brimfield Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 49 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 360 acres.
Explore East Brimfield Reservoir across LakeQuality
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Moderate nutrients, good water quality
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Where this data comes from
3 measurements from 1 monitoring station, 2016. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Massachusetts Department of Environmental Protection (MassDEP)
MASSDEP3 samples · 2016
Analytical methods
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)