Cottonwood #1 Reservoir Report

Last Updated: December 5, 2025

Cottonwood #1, located in Mesa County, Colorado, is a historic earth dam completed in 1894 for irrigation purposes along the Cottonwood Creek.


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Summary

With a height of 31 feet and a storage capacity of 2393 acre-feet, this dam plays a crucial role in water supply management in the region. It also serves for hydroelectric generation, recreation, and flood control, making it a multifunctional structure.

Despite its age, Cottonwood #1 has undergone modifications in 1960 and 2000 to enhance its hydraulic, mechanical, and structural features. The dam has a spillway width of 60 feet and is equipped with slide (sluice gate) outlet gates to manage water flow efficiently. While it has a hazard potential classified as high, the condition assessment in 2020 rated it as fair, indicating the need for ongoing monitoring and maintenance to ensure its safety and functionality for the community.

With its rich history and significant role in water resource management, Cottonwood #1 stands as a testament to the long-standing importance of dams in supporting agricultural and recreational activities while addressing the challenges of water supply and flood control in the region. As climate change continues to impact water resources, structures like Cottonwood #1 serve as vital infrastructure for sustainable water management and resilience against changing environmental conditions.

Years Modified

1960 - Hydraulic, 1960 - Mechanical, 1960 - Structural, 2000 - Hydraulic, 2000 - Structural

Year Completed

1894

Dam Length

410

Dam Height

31

River Or Stream

COTTONWOOD CREEK

Primary Dam Type

Earth

Surface Area

105

Hydraulic Height

29

Drainage Area

2

Nid Storage

2393

Structural Height

31

Outlet Gates

Slide (sluice gate) - 2

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

31
       
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.