Cottonwood #4 Reservoir Report

Last Updated: December 5, 2025

Cottonwood #4, located in Mesa County, Colorado, is a historic irrigation dam that was completed in 1896.


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Summary

Situated on Cottonwood Creek, this earth dam stands at a height of 17 feet and has a storage capacity of 541 acre-feet. Used for both hydroelectric power generation and irrigation purposes, the dam plays a crucial role in managing water resources in the region.

With a satisfactory condition assessment and a high hazard potential, Cottonwood #4 is subject to regular inspections and maintenance to ensure its structural integrity and public safety. The dam underwent significant modifications in 1985, including hydraulic, mechanical, and structural upgrades. The spillway, measuring 17 feet in width, is uncontrolled, with a maximum discharge capacity of 650 cubic feet per second.

Despite its age, Cottonwood #4 continues to serve its primary functions effectively, highlighting the importance of maintaining and managing aging infrastructure for water resource and climate enthusiasts. With a moderate risk assessment rating and a history of meeting regulatory guidelines, this dam remains a critical piece of Colorado's water management infrastructure.

Years Modified

1985 - Hydraulic, 1985 - Mechanical, 1985 - Structural

Year Completed

1896

Dam Length

288

Dam Height

17

River Or Stream

COTTONWOOD CREEK

Primary Dam Type

Earth

Surface Area

42

Hydraulic Height

16

Drainage Area

1

Nid Storage

541

Structural Height

22

Outlet Gates

Slide (sluice gate) - 1

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

22
       
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.