Grindstone River
Grindstone River is a gravity dam located in Pine County, Minnesota, built in 1955. It carries a Significant hazard potential classification and has a poor condition assessment.
About Grindstone River
The primary purpose of Grindstone River is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Mndnr-fisheries (state). It impounds the Grindstone River near Hinkley.
The dam stands 23 feet tall and stretches 58 feet across, creates a reservoir covering 20 acres, has a maximum storage capacity of 428 acre-feet, and collects water from a drainage area of 95 square miles. Completed in 1955, the structure is well into its service life at over 50 years 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 08/12/2020.
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Location
| State | Minnesota |
| County | Pine |
| Nearest City | Hinkley |
| River/Stream | Grindstone River |
| Coordinates | 46.02078, -92.94306 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 23 ft |
| Dam Height | 18 ft |
| Dam Length | 58 ft |
| Year Completed | 1955 (71 years old) |
Storage & Hydraulics
| NID Storage | 428 acre-ft |
| Max Storage | 428 acre-ft |
| Normal Storage | 305 acre-ft |
| Surface Area | 20 acres |
| Drainage Area | 95 sq mi |
| Max Discharge | 1,500 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | MNDNR-Fisheries |
| Owner Type | State |
| Hazard Classification | Significant |
| Condition Assessment | Poor |
| Last Inspection | 08/12/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MN00543 |
| Federal ID | MN00543 |
| More Info | State Dam Safety Program |