Pyramid Dam Reservoir Report

Last Updated: December 5, 2025

Pyramid Dam, located in TENSLEEP WY, Wyoming, is a gravity dam constructed in 2003 with a primary purpose listed as "Other." The dam, managed by the Bureau of Land Management, stands at a structural height of 30 feet and has a hydraulic height of 25 feet.


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Summary

It has a storage capacity of 59.21 acre-feet, with a normal storage level of 29.64 acre-feet.

Despite being classified as having a low hazard potential, Pyramid Dam is currently in poor condition, as reported in the last inspection in August 2016. The dam lacks an emergency action plan and has not been assessed for its condition in recent years. With a high risk assessment rating of 2, there is a need for improved risk management measures and updated emergency preparedness protocols for the dam.

Overall, Pyramid Dam serves as a critical water resource in Washakie, Wyoming, regulating the flow of the PYRAMID DRAW river. As a federal structure under the jurisdiction of the Bureau of Land Management, there is a call for increased attention to its maintenance and safety measures to ensure the continued protection of the surrounding communities and environment in the face of potential climate challenges.

Year Completed

2003

Dam Length

268

River Or Stream

PYRAMID DRAW

Primary Dam Type

Gravity

Surface Area

4.94

Hydraulic Height

25

Drainage Area

640

Nid Storage

59.21

Structural Height

30

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

30
       
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.