Cheshire Reservoir Dam Reservoir Report

Last Updated: December 6, 2025

Cheshire Reservoir Dam, also known as Prospect Reservoir Dam, is a concrete structure located in Mixville, Connecticut.


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Summary

Built in 1908 for the primary purpose of water supply, this dam stands at a height of 21 feet and spans 168 feet in length. It holds a maximum storage capacity of 58 acre-feet with a normal storage level of 30 acre-feet. The dam is situated on Mixville Brook in New Haven County and is owned by a public utility.

The Cheshire Reservoir Dam has a spillway width of 70 feet and a maximum discharge capability of 1086 cubic feet per second. It is regulated, permitted, inspected, and enforced by the Connecticut Department of Energy and Environmental Protection (DEEP). The dam has a high hazard potential due to its location and condition assessment, which was deemed satisfactory as of the last inspection in November 2019. The risk assessment for the dam is moderate (3) with no specific risk management measures outlined.

Despite its age, the Cheshire Reservoir Dam continues to serve as a vital water resource infrastructure in the region. With its historical significance, high hazard potential, and moderate risk assessment, the dam remains a focal point for water resource and climate enthusiasts interested in its maintenance and management for the future.

Year Completed

1908

Dam Length

168

Dam Height

21

River Or Stream

MIXVILLE BROOK

Primary Dam Type

Concrete

Surface Area

7

Drainage Area

1.76

Nid Storage

58

Hazard Potential

High

Nid Height

21
       
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.