Lake Mattawa South Dam
Lake Mattawa South Dam is an earth dam located in Franklin County, Massachusetts, built in 1893. It carries a Significant hazard potential classification and has a poor condition assessment.
About Lake Mattawa South Dam
The primary purpose of Lake Mattawa South Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Town Of Orange (local government). It impounds the Middle Branch Of Swift River near Orange.
The dam stands 10 feet tall and stretches 287 feet across, creates a reservoir covering 130 acres, has a maximum storage capacity of 928 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1893, the structure is over a century old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. An emergency action plan is in place for this dam. The most recent inspection on record was 11/19/2021.
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Location
| State | Massachusetts |
| County | Franklin |
| Nearest City | Orange |
| River/Stream | Middle Branch Of Swift River |
| Coordinates | 42.56281, -72.31671 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 10 ft |
| Dam Length | 287 ft |
| Year Completed | 1893 (133 years old) |
Storage & Hydraulics
| NID Storage | 928 acre-ft |
| Max Storage | 928 acre-ft |
| Normal Storage | 438 acre-ft |
| Surface Area | 130 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 419 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Town of Orange |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Poor |
| Last Inspection | 11/19/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MA00502 |
| Federal ID | MA00502 |
| More Info | State Dam Safety Program |