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Reservoirs in Massachusetts

64 of 829 measured Massachusetts lakes (8%) are man-made reservoirs in the USACE National Inventory of Dams. 51 carry a High or Significant hazard rating.

Reading the Massachusetts reservoir landscape

64 reservoirs in Massachusetts appear in the USACE National Inventory of Dams. That's a meaningful share — reservoir lakes carry their own ecology and access patterns distinct from natural lakes, including managed water levels, drawdowns timed to the dam's purpose, and shoreline mix dominated by structures built post-impoundment.

Recreation is the headline purpose for the largest share of Massachusetts's reservoirs — lakes where the dam exists explicitly to create surface water for fishing, boating, and adjacent shoreline development. Pool levels are typically maintained more stably than at flood-control or hydro reservoirs, which supports fixed-dock access, consistent boat ramps, and the kind of shoreline economy that natural-lake counterparts in the state share.

The USACE National Inventory of Dams (NID) catalogs every dam in the United States above a size threshold — typically 25 feet in height or 50 acre-feet in maximum storage, plus all dams classified as high-hazard regardless of size. The reservoir records below pull NID fields (year built, hazard class, maximum storage, surface area at normal pool, dam length, primary purpose) and pair them with water-quality data where the impoundment also appears in EPA's lake-monitoring inventory.

Why these Massachusetts reservoirs were built

Recreation

Water Supply

Flood Risk Reduction

Irrigation

Hydroelectric

Fire Protection, Stock, Or Small Fish Pond

Other

Total reservoirs

14,954

Total surface acres

288,855

Normal storage (ac-ft)

High or Significant hazard

All 64 Massachusetts reservoirs (by surface area)

Reservoir	County	Surface area	Year built	Purpose	Hazard
Wachusett Reservoir	Worcester	4,160 ac	1906	Water Supply	High
Webster Lake	Worcester	1,442 ac	1957	Recreation	Significant
Sudbury Reservoir	Worcester	1,300 ac	1899	Water Supply	High
Silver Lake	Plymouth	602 ac	1908	Water Supply	Low
Cambridge Reservoir	Middlesex	546 ac	1897	Water Supply	High
Hamilton Reservoir	Hampden	400 ac	—	Recreation	High
East Brimfield Reservoir	Worcester	360 ac	1960	Flood Risk Reduction	High
Bare Hill Pond	Worcester	324 ac	1837	Recreation	Significant
White Island Pond	Plymouth	322 ac	—	Irrigation	Significant
Ezekiel Pond	Plymouth	322 ac	—	Irrigation	Significant
Cleveland Pond	Plymouth	300 ac	1992	Recreation	Significant
Lake Pearl	Norfolk	288 ac	1920	Recreation	Significant
Ponkapoag Pond	Norfolk	285 ac	1930	Recreation	Significant
Walden Pond	Essex	243 ac	1890	Water Supply	High
Indian Lake	Worcester	233 ac	1920	Flood Risk Reduction	Significant
Sherman Reservoir	Franklin	218 ac	1927	Hydroelectric	High
Little River Lake	Worcester	200 ac	1958	Flood Risk Reduction	High
Upper Mystic Lake	Middlesex	185 ac	1860	Flood Risk Reduction	Significant
Crystal Lake	Essex	170 ac	1930	Water Supply	Significant
Santuit Pond	Barnstable	165 ac	—	Recreation	Low
Wrights Reservoir	Worcester	163 ac	1965	Flood Risk Reduction	High
Buckley-Dunton Lake	Berkshire	154 ac	1870	Recreation	High
Fitchburg Reservoir	Middlesex	153 ac	1916	Water Supply	Low
Nabnasset Pond	Middlesex	146 ac	1926	Recreation	Significant
Queen Lake	Worcester	142 ac	1824	Recreation	Significant
Upper Artichoke Reservoir	Essex	130.7 ac	1920	Water Supply	Low
Wachusett Lake	Worcester	130 ac	1905	Flood Risk Reduction	Significant
Stodge Meadow Pond	Worcester	125.8 ac	1863	Recreation	Low
Ten Mile River Lake	Bristol	111 ac	1890	Flood Risk Reduction	High
Ashley Lake	Berkshire	106 ac	1901	Water Supply	High
Wankinco River Lake	Plymouth	105 ac	—	Recreation	High
Horn Pond	Middlesex	103 ac	1989	Water Supply	Significant
Ames Long Pond	Bristol	94.7 ac	—	Recreation	Significant
Damon Pond	Hampshire	85 ac	1760	Recreation	Significant
Robbins Pond	Plymouth	85 ac	1930	Fire Protection, Stock, Or Small Fish Pond	Significant
Fall Brook Reservoir	Worcester	83 ac	1896	Water Supply	High
South Reservoir	Middlesex	80 ac	1882	Water Supply	High
Lower Spectacle Pond	Berkshire	70 ac	—	Recreation	Low
Muddy Brook Lake	Worcester	69 ac	—	Recreation	Significant
Sargent Pond	Worcester	66 ac	—	Recreation	Significant
West Branch Walker Brook Lake	Berkshire	65 ac	2013	Recreation	Significant
Tully Pond	Franklin	65 ac	—	Recreation	Significant
Watson Pond	Bristol	65 ac	—	Recreation	Significant
Stiles Pond	Essex	60 ac	1920	Recreation	Significant
Field Pond	Essex	57 ac	1930	Recreation	Significant
Long Pond	Barnstable	53 ac	1966	Recreation	Low
Atkins Reservoir	Franklin	51 ac	1930	Water Supply	High
Bartlett Pond	Worcester	44 ac	1885	Recreation	Low
Patch Reservoir	Worcester	34 ac	1896	Recreation	High
Card Pond	Berkshire	30.1 ac	1910	Recreation	High
Nashawannuck Pond	Hampshire	30 ac	—	Recreation	High
Windsor Lake	Berkshire	25 ac	1883	Recreation	High
Wedge Pond	Middlesex	21 ac	1900	Recreation	Low
Roaring Brook Lake	Franklin	20 ac	1975	Water Supply	High
Gaston Pond	Worcester	16 ac	1915	Recreation	Significant
Hallockville Pond	Franklin	16 ac	—	Recreation	Significant
Lower Crow Hill Pond	Worcester	13 ac	1956	Recreation	Significant
Vinica Pond	Hampden	10.6 ac	—	Recreation	Low
Billerica Impoundment Lake	Middlesex	8.6 ac	1828	Flood Risk Reduction	Significant
Lake Quinsigamond	Worcester	1.5 ac	1896	Recreation	Significant
Mashpee Pond	Barnstable	1 ac	—	Other	Significant
Congamond Lakes	Hartford	—	—	—	Undetermined
Cooks Pond	Plymouth	—	—	—	Undetermined
Fresh Pond	Plymouth	—	—	—	Undetermined

Frequently Asked Questions

How many reservoirs are in Massachusetts?

64 of 829 measured Massachusetts lakes (8%) are man-made reservoirs in the USACE National Inventory of Dams. 51 are rated High or Significant hazard, meaning failure would put downstream lives or property at substantial risk. The oldest matched dam dates to 1760.

What's the largest reservoir in Massachusetts?

The largest matched reservoir in Massachusetts is Wachusett Reservoir in Worcester County at 4,160 acres of normal surface area, impounded by the Wachusett Reservoir Dam (completed 1906).

What's the difference between a reservoir and a natural lake?

A reservoir is a body of water impounded by a man-made dam — typically built for flood control, hydroelectric power, water supply, irrigation, or recreation. A natural lake formed without human intervention, usually from glacial scouring, volcanic activity, or river meandering. Reservoirs typically have shoreline that fluctuates with seasonal water level management, while natural lakes have more stable shorelines. The USACE National Inventory of Dams classifies every regulated dam in the United States, which is how we identify which LakeQuality lakes are actually reservoirs.

What does the hazard class mean?

USACE assigns each dam a hazard potential classification based on what would happen downstream if the dam failed — NOT how likely the dam is to fail. "Low" hazard means dam failure would cause no probable loss of life and only low economic loss. "Significant" means probable loss of life is unlikely but appreciable economic damage would occur. "High" means probable loss of life and significant economic damage. The classification is about consequence, not condition. Many High-hazard dams are perfectly safe; they're rated High because populated areas have grown downstream over time.

Where does this reservoir data come from?

Every reservoir record on this page is matched to the USACE National Inventory of Dams (NID), the federal database of all dams ≥25 ft tall or impounding ≥50 acre-feet, plus any dam that poses a Significant or High hazard regardless of size. The NID is published by the U.S. Army Corps of Engineers and updated annually. Surface area, storage capacity, dam height, and hazard classification come directly from NID records.

Where to stay near Massachusetts reservoirs

Compare cabins, lodges, and vacation rentals near the largest reservoirs in Massachusetts — live availability and prices for boating, fishing, and lake trips.

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More on reservoirs and water quality

Are Reservoirs Cleaner Than Natural Lakes?

Dam-built reservoirs and natural lakes compared side by side on the same nutrient and algae measurements — the gap, the reasons behind it, and the exceptions.

Do Deeper Lakes Have Better Water Quality?

Surveyed maximum depth against nutrient and algae readings: the pattern, the shallow lakes that still read clean, and why land use beats bathymetry.

Lake Water Quality Explained: What the Readings Mean

How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading is not a clearance.

Why Lakes Turn Green: Phosphorus and Nutrient Pollution

How phosphorus and nutrient runoff drive algae growth and turn lakes green, where the nutrients come from, and what it means for a lake’s readings.

Data source

Reservoir data from the USACE National Inventory of Dams (NID), the federal database of all regulated dams. Dam attributes (height, year completed, storage capacity, hazard class) are matched to LakeQuality lakes by proximity and dam-name similarity. Some lakes may be reservoirs that aren't matched if the dam record uses a name substantially different from our lake name.