Trego is a gravity dam located in Washburn County, Wisconsin, built in 1927. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 39 ft39 ft tall and 625 ft long, taller than 85% 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 concrete gravity section and the water level is illustrative.
About Trego
The primary purpose of Trego is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Northern States Power Co (public utility). It impounds the Namekagon River near Riverside.
The dam stands 39 feet tall and stretches 625 feet across, creates a reservoir covering 470 acres, has a maximum storage capacity of 4,700 acre-feet, and collects water from a drainage area of 488 square miles. Completed in 1927, the structure is well-established, with more than 75 years of service.
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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 09/21/2022.
At 39 feet, this dam is taller than 85% of dams nationwide.
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Location
| State | Wisconsin |
| County | Washburn |
| Nearest City | Riverside |
| River/Stream | Namekagon River |
| Coordinates | 45.94830, -91.88790 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 39 ft |
| Dam Height | 39 ft |
| Dam Length | 625 ft |
| Year Completed | 1927 (99 years old) |
Storage & Hydraulics
| NID Storage | 4,700 acre-ft |
| Max Storage | 4,700 acre-ft |
| Normal Storage | 4,700 acre-ft |
| Surface Area | 470 acres |
| Drainage Area | 488 sq mi |
| Max Discharge | 9,240 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Northern States Power Co |
| Owner Type | Public Utility |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 09/21/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WI00812 |
| Federal ID | WI00812 |
| More Info | State Dam Safety Program |