Middle Cottonwood Reservoir Report

Last Updated: December 5, 2025

Middle Cottonwood is a federal-owned structure located in Thermopolis, Wyoming, within the Fremont County.


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Summary

Built in 1975, this dam serves the primary purpose of a Fish and Wildlife Pond, with additional functions including Fire Protection, Stock, Irrigation, and more. Managed by the Bureau of Reclamation, Middle Cottonwood has a storage capacity of 613 acre-feet and covers a surface area of 117 acres.

With a low hazard potential and a high risk assessment rating of 2, Middle Cottonwood is equipped with a Slide (sluice gate) outlet gate and stands at a structural height of 14 feet. The dam regulates the Cottonwood Drain Draw and offers a maximum discharge of 14,800 cubic feet per second. Despite its critical role in the region, the current condition assessment of Middle Cottonwood is listed as "Not Available," highlighting the need for further inspection and risk management measures to ensure its continued safety and functionality.

Water resource and climate enthusiasts will find Middle Cottonwood to be a fascinating structure within the Bureau of Reclamation's portfolio, contributing to the local ecosystem as a fish and wildlife habitat. With its strategic location and vital functions, this dam represents a vital component of water management in the region, requiring ongoing monitoring and maintenance to uphold its integrity and safeguard against potential risks.

Year Completed

1975

Dam Height

27

River Or Stream

COTTONWOOD DRAIN DRAW

Primary Dam Type

Other

Surface Area

117

Hydraulic Height

12

Drainage Area

1

Nid Storage

613

Structural Height

14

Outlet Gates

Slide (sluice gate) - 1

Hazard Potential

Low

Nid Height

27
       
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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.