Trego Reservoir Report

Last Updated: December 5, 2025

Trego is a captivating hydroelectric dam located on the Namekagon River in Wisconsin, specifically in the city of Riverside.


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Summary

Completed in 1927, this gravity dam stands at 39 feet in height and stretches 625 feet in length, with a storage capacity of 4,700 acre-feet and a maximum discharge of 9,240 cubic feet per second. The dam serves multiple purposes, including hydroelectric power generation and recreation, making it a vital resource for both energy production and outdoor activities in the region.

Managed by the Federal Energy Regulatory Commission, Trego is a significant structure with a hazard potential classified as "Significant" and a risk assessment rating of "Very High (1)." Despite its age, the dam's condition assessment is currently listed as "Not Available," indicating a need for further evaluation. The spillway width of 81 feet and the presence of multiple outlet gates, including slide and tainter gates, contribute to the dam's operational efficiency and safety measures. With its historical significance and ongoing role in water resource management, Trego remains a focal point for water resource and climate enthusiasts interested in sustainable energy solutions and infrastructure resilience.

Year Completed

1927

Dam Length

625

Dam Height

39

River Or Stream

Namekagon River

Primary Dam Type

Gravity

Surface Area

470

Drainage Area

488

Nid Storage

4700

Structural Height

29

Outlet Gates

Slide (sluice gate) - 1, Tainter (radial) - 3

Hazard Potential

Significant

Foundations

Soil

Nid Height

39
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.