Thorson Group North is an earth dam located in Houston County, Minnesota, built in 1963. It carries a Significant hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 30 ft30 ft tall and 440 ft long, taller than 68% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Thorson Group North
The primary purpose of Thorson Group North is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Mndnr-forestry (state). It impounds the Root River S Fork-tr near Hokah.
The dam stands 30 feet tall and stretches 440 feet across, has a maximum storage capacity of 45 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1963, 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. The most recent inspection on record was 04/26/2023.
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Location
| State | Minnesota |
| County | Houston |
| Nearest City | Hokah |
| River/Stream | Root River S Fork-tr |
| Coordinates | 43.72957, -91.62834 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 30 ft |
| Dam Height | 28 ft |
| Dam Length | 440 ft |
| Year Completed | 1963 (63 years old) |
Storage & Hydraulics
| NID Storage | 45 acre-ft |
| Max Storage | 45 acre-ft |
| Drainage Area | 0 sq mi |
| Max Discharge | 800 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Mndnr-forestry |
| Owner Type | State |
| Hazard Classification | Significant |
| Condition Assessment | Poor |
| Last Inspection | 04/26/2023 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MN00343 |
| Federal ID | MN00343 |
| More Info | State Dam Safety Program |