Massachusetts Dams
1,291 dams tracked by the National Inventory of Dams
Total Dams
1,291
High Hazard
319
24.7%
Poor / Unsatisfactory
336
Average Age
112 yrs
Hazard Classification
High319 (24.7%)
Significant616 (47.7%)
Low356 (27.6%)
Condition Assessment
Satisfactory441 (34.2%)
Fair464 (35.9%)
Poor / Unsatisfactory336 (26.0%)
Not Rated50 (3.9%)
Federal
15
State
211
Local
585
Private
451
Tallest Dams
- Cobble Mountain Reservoir Dam245 ft
- Quabbin Winsor Dam170 ft
- Littleville Dam164 ft
- Bear Swamp - North Dike 155 ft
- Knightville Dam150 ft
High Hazard Dams
Poor Condition Dams
All Dams in Massachusetts
Showing 451–475 of 1,291
| Dam Name | Height (ft) | Year | Hazard | Condition |
|---|---|---|---|---|
| Otter River Dam Worcester County | 10 | 1946 | Low | Poor |
| Otis Woodlands Club Dam Berkshire County | 22 | — | Significant | Satisfactory |
| Otis Reservoir Dam Berkshire County | 32 | 1888 | High | Satisfactory |
| Osgood Pond Dam Essex County | 28 | — | Significant | Poor |
| Ortolani Reservoir No. 3 Dam Plymouth County | 13 | 1910 | Low | Fair |
| Ortolani No. 2 Dam Plymouth County | 13 | 1900 | Low | Not Rated |
| Orrs Pond Dam Bristol County | 18 | 1906 | Low | Fair |
| Onota Lake Dam Berkshire County | 18 | 1865 | High | Satisfactory |
| Old Water Supply Dam Middlesex County | 13 | 1900 | Significant | Satisfactory |
| Old Shepard Pond Dam Worcester County | 7 | — | Low | Fair |
| Old Pond Dam Bristol County | 9 | 1751 | Significant | Poor |
| Old Oaken Bucket Pond Dam Plymouth County | 6 | 1640 | Significant | Satisfactory |
| Old Mill Pond Dam Worcester County | 15 | 1800 | Significant | Satisfactory |
| Old Mill Pond Dam Dukes County | 5 | — | Significant | Satisfactory |
| Old Mill Pond Dam Worcester County | 18 | — | Significant | Poor |
| Old Mill Pond Dam Worcester County | 13 | — | Significant | Poor |
| Old Grist Mill Pond Dam Worcester County | 19 | 1953 | Significant | Fair |
| Old Grist Mill Pond Dam Bristol County | 12 | 1745 | High | Satisfactory |
| Old Duck Pond Dam Worcester County | 12 | — | Significant | Poor |
| October Mountain Lake Dike Berkshire County | 20 | 1985 | High | Satisfactory |
| October Mountain Lake Dam Berkshire County | 39 | 1972 | High | Satisfactory |
| Ocean Spray Dam Plymouth County | 13 | — | Low | Not Rated |
| O'Brien Pond Dam Hampshire County | 13 | — | Significant | Poor |
| Oakman Pond Dam Plymouth County | 13 | — | Significant | Satisfactory |
| Nye Pond Dam Barnstable County | 11 | 1669 | Significant | Poor |
Data sourced from the National Inventory of Dams (NID). Hazard classification reflects potential consequences of failure, not the likelihood of failure.