Wilder Reservoir Report

Last Updated: December 13, 2025

Wilder is a captivating hydroelectric dam located on the Connecticut River in West Lebanon, New Hampshire.


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Summary

Completed in 1950, this concrete dam stands at a height of 59 feet and spans 2900 feet in length. With a storage capacity of 55,000 acre-feet and a maximum discharge of 302,000 cubic feet per second, Wilder plays a crucial role in harnessing the power of the river for electricity generation and recreational activities.

Managed by the New Hampshire Department of Environmental Services Dam Bureau and regulated by the Federal Energy Regulatory Commission, Wilder poses a high hazard potential due to its structural design and location. The dam features a controlled spillway with a width of 241 feet and a system of slide and Tainter gates for water release. Despite its high-risk classification, current condition assessment information is not available, emphasizing the need for regular inspections and emergency preparedness measures to mitigate potential risks to downstream communities.

Wilder serves as a prime example of balancing the benefits of hydroelectric power generation with the responsibilities of dam safety and environmental stewardship. With its strategic location, impressive engineering design, and critical role in water resource management, Wilder stands as a testament to the intersection of human ingenuity and the forces of nature in shaping our energy landscape.

Year Completed

1950

Dam Length

2900

Dam Height

59

River Or Stream

Connecticut River

Primary Dam Type

Concrete

Surface Area

3100

Drainage Area

3375

Nid Storage

55000

Outlet Gates

Slide (sluice gate) - 2, Tainter (radial) - 6

Hazard Potential

High

Nid Height

59
       
Seasonal Comparison

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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.