Rainbow Lake Dam Reservoir Report

Last Updated: December 14, 2025

Rainbow Lake Dam, located in Indian Lake, Hamilton County, New York, is a concrete dam built in 1929 primarily for recreational purposes.


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Summary

Standing at a height of 25 feet and spanning 75 feet in length, the dam holds a storage capacity of 97 acre-feet, with a normal storage level of 38 acre-feet. The dam is situated on Big Brook, within the Buffalo District of New York.

Despite its recreational significance, Rainbow Lake Dam poses a high hazard potential and has been assessed to be in poor condition as of March 2017. The dam's spillway is uncontrolled with a width of 19 feet, and its risk assessment indicates a moderate risk level. Regular inspections are conducted, with the latest inspection done in November 2020, and an emergency action plan was last reviewed in February 2021.

With its historical significance, scenic location, and recreational value, Rainbow Lake Dam serves as both a water resource and climate enthusiasts' attraction while also highlighting the importance of ongoing maintenance and monitoring to ensure public safety and environmental sustainability.

Year Completed

1929

Dam Length

75

Dam Height

25

River Or Stream

BIG BROOK

Primary Dam Type

Concrete

Surface Area

15

Drainage Area

8.79

Nid Storage

97

Hazard Potential

High

Nid Height

25
       
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.