Cottonwood Lake Reservoir Report

Last Updated: December 4, 2025

Cottonwood Lake, located in Colorado's Chaffee County, is a stunning reservoir nestled along the South Cottonwood Creek.


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Summary

Managed by the USDA Forest Service, this concrete dam was completed in 1936 for the primary purpose of recreation, offering visitors a serene escape surrounded by nature. With a low hazard potential and a moderate risk assessment, the dam stands at 6 feet high and has a storage capacity of 120 acre-feet, making it a picturesque destination for water resource and climate enthusiasts.

The dam at Cottonwood Lake boasts a gravity design and a spillway type of "Uncontrolled," with a structural height of 8 feet and a hydraulic height of 3 feet. While the dam's surface area is listed as 0, it covers a drainage area of 26 square miles and can discharge up to 540 cubic feet per second. Despite not being state regulated, the dam undergoes inspections every 10 years, with the last one taking place in September 2013. With its tranquil surroundings and recreational offerings, Cottonwood Lake is a must-visit destination for those interested in water management and sustainable leisure activities.

Whether you're drawn to the beauty of concrete structures or fascinated by the dynamics of reservoirs, Cottonwood Lake is a prime example of a well-maintained water resource managed by the Forest Service. While its condition assessment is currently marked as "Not Rated," the dam's risk assessment remains moderate, symbolizing the careful management and upkeep of this recreational gem. With its rich history dating back to the 1930s, Cottonwood Lake continues to attract visitors seeking a peaceful retreat and a deeper understanding of water infrastructure in a natural setting.

Year Completed

1936

Dam Length

41

Dam Height

6

River Or Stream

SOUTH COTTONWOOD CREEK

Primary Dam Type

Concrete

Hydraulic Height

3

Drainage Area

26

Nid Storage

120

Structural Height

8

Hazard Potential

Low

Nid Height

8
       
Seasonal Comparison

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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.