Souhegan River Site 12a North Dike Reservoir Report

Last Updated: December 17, 2025

Souhegan River Site 12a North Dike, also known as Senator Charles W Tobey Dam, is a state-owned structure in Temple, New Hampshire, designed by USDA NRCS to reduce flood risks along the Miller Gamble River.


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Summary

Completed in 1965, this earth dam stands at a height of 38.7 feet and has a storage capacity of 3,310 acre-feet. The dam's primary purpose is flood risk reduction, with a fair condition assessment and a high hazard potential.

Managed by the NHDES Dam Bureau, Souhegan River Site 12a North Dike is regulated, permitted, inspected, and enforced by the state of New Hampshire to ensure its safety and functionality. Despite its age, the dam continues to serve its purpose effectively, with a moderate risk assessment rating. With a drainage area of 5.4 square miles and a spillway width of 12 feet, this dam plays a crucial role in mitigating potential flooding events and protecting the surrounding community. For water resource and climate enthusiasts, this site offers a fascinating glimpse into the intersection of infrastructure, environmental protection, and public safety.

Year Completed

1965

Dam Length

1185

Dam Height

38.7

River Or Stream

MILLER GAMBLE RIVER

Primary Dam Type

Earth

Surface Area

108

Drainage Area

5.4

Nid Storage

3310

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

39
       
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.