D.f. Riley Grist Mill Dam
D.f. Riley Grist Mill Dam is a stone dam located in Hampshire County, Massachusetts, built in 1881. It carries a Significant hazard potential classification and has a unsatisfactory condition assessment.
About D.f. Riley Grist Mill Dam
The primary purpose of D.f. Riley Grist Mill Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Mill River Storage, Llc;old Mill Enterprises, Llc (private). It impounds the Mill River near Hatfield.
The dam stands 16 feet tall and stretches 200 feet across, creates a reservoir covering 58 acres, has a maximum storage capacity of 860 acre-feet, and collects water from a drainage area of 47 square miles. Completed in 1881, 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 unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. The most recent inspection on record was 05/22/2019.
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Location
| State | Massachusetts |
| County | Hampshire |
| Nearest City | Hatfield |
| River/Stream | Mill River |
| Coordinates | 42.37147, -72.60830 |
Physical Characteristics
| Dam Type | Stone |
| NID Height | 16 ft |
| Dam Length | 200 ft |
| Year Completed | 1881 (145 years old) |
Storage & Hydraulics
| NID Storage | 860 acre-ft |
| Max Storage | 860 acre-ft |
| Normal Storage | 580 acre-ft |
| Surface Area | 58 acres |
| Drainage Area | 47 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Mill River Storage, LLC;Old Mill Enterprises, LLC |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 05/22/2019 |
| Emergency Action Plan | No |
Identifiers
| NID ID | MA00493 |
| Federal ID | MA00493 |
| More Info | State Dam Safety Program |