Lower Robertson Reservoir Report

Last Updated: December 12, 2025

Lower Robertson is a private hydroelectric dam located in Hinsdale, New Hampshire, along the Ashuelot River.


°F

°F

mph

Wind

%

Humidity

Summary

Built in 1905, this dam stands at a height of 18 feet and has a storage capacity of 100 acre-feet. With a controlled spillway and a maximum discharge of 10,200 cubic feet per second, this dam plays a crucial role in both water resource management and energy generation in the region.

Managed by the NHDES Dam Bureau and regulated by the Federal Energy Regulatory Commission, Lower Robertson is inspected regularly to ensure its structural integrity and compliance with safety standards. Despite being classified as a low hazard potential structure, this dam is considered to have a very high risk (level 1) due to its age and potential impact on the surrounding area in the event of a failure. Emergency action plans have been prepared, but the condition assessment and risk management measures are currently not available, highlighting the importance of ongoing monitoring and maintenance to protect both the environment and the community.

Enthusiasts interested in water resources and climate change will find Lower Robertson to be a fascinating case study in the intersection of infrastructure, regulation, and risk management. The history and ongoing management of this dam offer valuable insights into the challenges and opportunities associated with balancing the benefits of hydroelectric power generation with the need to protect against potential hazards and ensure the long-term sustainability of water resources in the region.

Year Completed

1905

Dam Length

349

Dam Height

18

River Or Stream

Ashuelot River

Surface Area

9

Drainage Area

406

Nid Storage

100

Outlet Gates

Needle - 1, Other Controlled - 1

Hazard Potential

Low

Nid Height

18
       
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.