Deep Hollow Reservoir Dam Reservoir Report

Last Updated: December 5, 2025

Deep Hollow Reservoir Dam, also known as Wilcox Reservoir, is a historic masonry dam located in Chester, Connecticut.


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Summary

Built in 1854, this dam serves as a crucial water supply source for the region, with a storage capacity of 255 acre-feet and a normal storage level of 200 acre-feet. The dam stands at a height of 28 feet and spans 352 feet, creating a surface area of 27.5 acres and draining a 4.07 square mile watershed.

Managed by the Connecticut Department of Energy and Environmental Protection (DEEP), Deep Hollow Reservoir Dam is considered to have a significant hazard potential but has been deemed to be in satisfactory condition as of the last assessment in October 2019. The dam has a spillway width of 88 feet and a maximum discharge capacity of 509 cubic feet per second. With regular inspections and adherence to state regulations, the dam continues to play a vital role in water resource management and climate resilience efforts in the area.

Deep Hollow Reservoir Dam's rich history, combined with its continued functionality as a water supply structure, makes it a site of interest for water resource and climate enthusiasts. As a key component of the region's infrastructure, this masonry dam stands as a testament to the importance of sustainable water management practices and the critical role dams play in supporting communities and ecosystems in the face of changing climate conditions.

Year Completed

1854

Dam Length

352

Dam Height

28

River Or Stream

GREAT BROOK

Primary Dam Type

Masonry

Surface Area

27.5

Drainage Area

4.07

Nid Storage

255

Hazard Potential

Significant

Nid Height

28
       
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.
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