Updated Aug 2026
Massachusetts Lake Water Quality
Water quality grades for 105 monitored lakes across 12 counties.
105 Massachusetts lakes carry a grade. Most of the input data flows through monitoring run by the Massachusetts Department of Environmental Protection, which feeds state, federal, and volunteer measurements into the EPA Water Quality Portal. Roughly 35% of the state's graded lakes carry an A — 37 lakes that earn the top bracket on the combined Secchi/phosphorus/chlorophyll-a rubric. That share is high by national standards and reflects the depth and natural clarity of glacial lakes in the region.
Mesotrophic is the dominant trophic class — a workable middle ground between the pristine oligotrophic deep lakes and the algal-pressured eutrophic shallow ones. Franklin ranks highest on average county grade (A). Bristol sits lowest. With only 12 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Grade Distribution
All 105 Massachusetts lakes in the index: 83 (79.0%) carry an A–F grade and 22 (21.0%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
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Top-Graded Massachusetts Lakes
The highest water-quality grades in Massachusetts — clarity, depth, and A-F grade at a glance.
Lake Map
Explore Massachusetts Lakes
Massachusetts reports, fishing & travel
Reservoirs in Massachusetts
View all 64 reservoirs →64 of 105 Massachusetts lakes (61%) are man-made reservoirs in the USACE National Inventory of Dams. 51 carry a High or Significant hazard rating. The oldest matched dam dates to 1760.
EPA-Impaired Lakes in Massachusetts
View all 100 impaired lakes →100 of 105 Massachusetts lakes (95%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 33 have an approved Total Maximum Daily Load (TMDL) restoration plan.
Massachusetts Fishing & Recreation
Licenses, regulations, records, and where to fish across Massachusetts.
Counties
All 12 Massachusetts counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of graded lakes, or pick a different state.
Top 25 Cleanest Lakes
25 lakes25 graded lakes
| # | Lake | County | Grade | Clarity | Trophic | Access |
|---|---|---|---|---|---|---|
| 1 | ALong Pond | Worcester | A | No recent samples | Oligotrophic | ✓ Public |
| 2 | ALong Pond | Barnstable | A | No recent samples | Mesotrophic | Not recorded |
| 3 | AGaston Pond | Worcester | A | No recent samples | Mesotrophic | Not recorded |
| 4 | ABare Hill Pond | Worcester | A | No recent samples | Mesotrophic | Not recorded |
| 5 | AArcadia Lake | Hampshire | A | No recent samples | Oligotrophic | Not recorded |
| 6 | ACard Pond | Berkshire | A | No recent samples | Mesotrophic | ✓ Public |
| 7 | AQueen Lake | Worcester | A | No recent samples | Mesotrophic | Not recorded |
| 8 | ARoaring Brook Lake | Franklin | A | No recent samples | Mesotrophic | Not recorded |
| 9 | ABenton Pond | Berkshire | A | No recent samples | Mesotrophic | ✓ Public |
| 10 | AWrights Reservoir | Worcester | A | No recent samples | Mesotrophic | Not recorded |
| 11 | AAshley Lake | Berkshire | A | No recent samples | Mesotrophic | Not recorded |
| 12 | AQuacumquasit Pond | Worcester | A | No recent samples | Mesotrophic | ✓ Public |
| 13 | AHamilton Reservoir | Hampden | A | No recent samples | Mesotrophic | ✓ Public |
| 14 | AAtkins Reservoir | Franklin | A | No recent samples | Mesotrophic | Not recorded |
| 15 | AWest Branch Walker Brook Lake | Berkshire | A | No recent samples | Mesotrophic | Not recorded |
| 16 | ATully Pond | Franklin | A | No recent samples | Mesotrophic | Not recorded |
| 17 | AHallockville Pond | Franklin | A | No recent samples | Oligotrophic | ✓ Public |
| 18 | ADamon Pond | Hampshire | A | No recent samples | Mesotrophic | Not recorded |
| 19 | ASouth Reservoir | Middlesex | A | No recent samples | Mesotrophic | Not recorded |
| 20 | ALily Pond | Worcester | A | No recent samples | Oligotrophic | Not recorded |
| 21 | ARobbins Pond | Plymouth | A | No recent samples | Mesotrophic | Not recorded |
| 22 | ALake Pearl | Norfolk | A | No recent samples | Oligotrophic | Not recorded |
| 23 | AFall Brook Reservoir | Worcester | A | No recent samples | Oligotrophic | Not recorded |
| 24 | AWalden Pond | Essex | A | No recent samples | Mesotrophic | Not recorded |
| 25 | AFitchburg Reservoir | Middlesex | A | No recent samples | Mesotrophic | Not recorded |
25 Lakes Needing Attention
25 lakes25 graded lakes
| # | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | FWedge Pond | Middlesex | F | No recent samples |
| 2 | FSouth Watuppa Pond | Bristol | F | No recent samples |
| 3 | FCooks Pond | Plymouth | F | No recent samples |
| 4 | FMill Pond | Barnstable | F | No recent samples |
| 5 | FFurnace Pond | Plymouth | F | No recent samples |
| 6 | FBarkers Pond | Middlesex | F | No recent samples |
| 7 | FGleasons Pond | Middlesex | F | No recent samples |
| 8 | FBartlett Pond | Worcester | F | No recent samples |
| 9 | FNashawannuck Pond | Hampshire | F | No recent samples |
| 10 | DHorn Pond | Middlesex | D | No recent samples |
| 11 | DSpy Pond | Middlesex | D | No recent samples |
| 12 | DAmes Long Pond | Bristol | D | No recent samples |
| 13 | DTen Mile River Lake | Bristol | D | No recent samples |
| 14 | DCleveland Pond | Plymouth | D | No recent samples |
| 15 | DBoons Pond | Middlesex | D | No recent samples |
| 16 | DHeart Pond | Middlesex | D | No recent samples |
| 17 | DUpper Artichoke Reservoir | Essex | D | No recent samples |
| 18 | DLittle Chauncy Pond | Worcester | D | No recent samples |
| 19 | DStiles Pond | Essex | D | No recent samples |
| 20 | DStodge Meadow Pond | Worcester | D | No recent samples |
| 21 | DRobbins Pond | Worcester | D | No recent samples |
| 22 | DMuddy Brook Lake | Worcester | D | No recent samples |
| 23 | DPequot Pond | Hampden | D | No recent samples |
| 24 | DLower Spectacle Pond | Berkshire | D | No recent samples |
| 25 | DCongamond Lakes | Hartford | D | No recent samples |
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
The top-graded lake in every state we cover, picked grade-first with water clarity as the tie-breaker — plus the states whose winner is still not clean.
State-by-state Secchi champions: the clearest measured lake in each U.S. state we grade, which is not the same as the cleanest nutrient grade.
A data snapshot of the lakes we grade: how the A–F distribution breaks down, the clearest and the greenest states, and where the water is improving.
How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.