Weston Reservoir Report
Last Updated: December 15, 2025
Weston, also known as Lower Groveton Dam, is a private hydroelectric structure located on the Upper Ammonoosuc River in Groveton, New Hampshire.
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Summary
Built in 1987, this timber crib dam stands at 20 feet tall and stretches 210 feet in length, with a storage capacity of 275 acre-feet. Managed by the New Hampshire Department of Environmental Services Dam Bureau, Weston is classified as a low hazard potential structure with a moderate risk assessment rating.
The Federal Energy Regulatory Commission oversees Weston's operations and inspections, ensuring its compliance with safety regulations. The dam features an uncontrolled spillway with a width of 118 feet, and is equipped with four slide (sluice) gates for water release. While the dam's condition assessment is currently not available, its last inspection was conducted in January 2021. With a drainage area of 263 square miles and a maximum discharge capacity of 14,250 cubic feet per second, Weston plays a crucial role in the region's hydroelectric power generation and water resource management.
Despite its low hazard potential, Weston remains an essential piece of infrastructure for the surrounding community, providing renewable energy and contributing to the overall water resource management in the area. Its strategic location on the Upper Ammonoosuc River highlights the importance of sustainable hydropower development and the need for effective dam oversight to ensure public safety and environmental conservation. As climate change continues to impact water resources, structures like Weston will play a key role in adapting to and mitigating its effects on the local ecosystem.
Year Completed |
1987 |
Dam Length |
210 |
Dam Height |
20 |
River Or Stream |
Upper Ammonoosuc River |
Primary Dam Type |
Timber Crib |
Surface Area |
30 |
Drainage Area |
263 |
Nid Storage |
275 |
Outlet Gates |
Slide (sluice gate) - 4 |
Hazard Potential |
Low |
Nid Height |
20 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Percy Loop Tentsite
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Maidstone State Park
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Unknown Pond Tentsite
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Unknown Pond Campsite
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Mt Cabot Cabin
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Rogers Ledge Campsite
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Weston
Bridge Street Guildhall