York Reservoir Report

Last Updated: December 18, 2025

Located in Boscawen, New Hampshire, the York Dam, also known as Contoocook Park Dam, is a state-owned structure regulating the flow of the Contoocook River.


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Summary

Built in 1967 for hydroelectric purposes, this concrete gravity dam stands at 10 feet tall and spans 230 feet in length. With a storage capacity of 500 acre-feet, it serves as a crucial component of the region's water resource management system.

Managed by the New Hampshire Department of Environmental Services Dam Bureau and regulated by both state and federal agencies, including the Federal Energy Regulatory Commission, the York Dam plays a vital role in ensuring safe and efficient water flow and storage. Despite being classified as having a low hazard potential, the dam is subject to regular inspections and monitoring to maintain its structural integrity and operational effectiveness. The risk assessment for the dam is moderate, highlighting the importance of continued oversight and maintenance to mitigate potential risks.

In the event of an emergency, the dam is equipped with an uncontrolled spillway with a width of 170 feet to manage excess water flow. While the condition assessment of the dam is currently not available, emergency action plans have been prepared and updated in accordance with guidelines. Overall, the York Dam stands as a key infrastructure asset in the region's water resource management efforts, providing both hydroelectric power generation and flood control benefits to the surrounding communities.

Year Completed

1967

Dam Length

230

Dam Height

10

River Or Stream

Contoocook River

Surface Area

50

Drainage Area

760

Nid Storage

500

Hazard Potential

Low

Nid Height

10
       
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.