Blackwater Dam - Dodge Estate Dike Reservoir Report

Last Updated: December 19, 2025

Blackwater Dam - Dodge Estate Dike, also known as the Dry Reservoir, is a federal structure located in Webster, New Hampshire along the Blackwater River.


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Summary

Completed in 1941, this gravity dam stands at 18 feet high and spans 400 feet in length, with a dam volume of 299,000 cubic feet. With a primary purpose of flood risk reduction, the dam has a maximum storage capacity of 93,400 acre-feet and can discharge up to 42,800 cubic feet of water per second through an uncontrolled spillway.

Managed by the US Army Corps of Engineers, the dam poses a high hazard potential and undergoes inspections every 5 years. While the condition assessment is not available, emergency preparedness measures are in place, including an Emergency Action Plan (EAP) and regular risk management activities. The USACE works to mitigate flood risks associated with the dam by monitoring its health, prioritizing risk-reducing activities, and collaborating with local emergency managers to raise awareness and develop emergency response plans.

Despite their efforts, dams like Blackwater Dam are not immune to the impacts of severe weather events or flooding. The USACE's goal is to address all types of flood risks by managing water levels, releasing water as needed, and ensuring the structural integrity of the dam. As they continue to monitor and maintain the dam, additional information specific to Blackwater Dam's risk management strategies will be provided in the future.

Year Completed

1941

Dam Length

400

Dam Height

18

River Or Stream

BLACKWATER RIVER

Primary Dam Type

Gravity

Surface Area

1

Hydraulic Height

13

Drainage Area

128

Nid Storage

93400

Structural Height

18

Hazard Potential

High

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.