Willimantic Reservoir Dam Reservoir Report
Last Updated: December 6, 2025
The Willimantic Reservoir Dam, located in Willimantic, Connecticut, is a key structure managed by the local government for water supply purposes.
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Summary
Constructed in 1885, this concrete dam stands at a height of 29 feet and has a length of 491.3 feet. The reservoir has a maximum storage capacity of 1670 acre-feet, with a normal storage level of 750 acre-feet, serving the surrounding area for water needs.
The dam, situated on the Natchaug River, is regulated by the Connecticut Department of Energy and Environmental Protection (DEEP) and undergoes regular inspections to ensure its safety and functionality. With a high hazard potential but deemed to be in satisfactory condition as of the last assessment in 2019, the Willimantic Reservoir Dam plays a critical role in water resource management in the region. Its location in Windham County, under the oversight of local authorities and state agencies, highlights the collaborative efforts to safeguard this vital infrastructure.
This historic dam not only provides crucial water storage but also contributes to flood control and water resource management in the area. With a spillway width of 280 feet and a maximum discharge capacity of 38,125 cubic feet per second, the Willimantic Reservoir Dam is a significant piece of infrastructure that ensures water security for the community while adhering to state regulatory standards. As climate change impacts water resources, the maintenance and oversight of structures like the Willimantic Reservoir Dam become increasingly important in ensuring resilience against changing environmental conditions.
Year Completed |
1885 |
Dam Length |
491.3 |
Dam Height |
29 |
River Or Stream |
NATCHAUG RIVER |
Primary Dam Type |
Concrete |
Surface Area |
100 |
Drainage Area |
166 |
Nid Storage |
1670 |
Hazard Potential |
High |
Nid Height |
29 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Natchaug River At Willimantic
|
257cfs |
Shetucket River Near Willimantic
|
588cfs |
Willimantic River Near Coventry
|
157cfs |
Mount Hope River Near Warrenville
|
30cfs |
Little River Near Hanover
|
34cfs |
Yantic River At Yantic
|
115cfs |
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.
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