Three Forks Dam Reservoir Report

Last Updated: December 13, 2025

Three Forks Dam, located in Natrona, Wyoming, is a gravity dam primarily designed for debris control on the MIKE WASH river.


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Summary

Completed in 1954 by the Bureau of Land Management, this federal-owned structure stands at a hydraulic height of 29 feet and a structural height of 36 feet, with a length of 270 feet. The dam has a storage capacity of 29.8 acre-feet, with a normal storage level of 15 acre-feet and a surface area of 3.4 acres.

Despite its low hazard potential, Three Forks Dam has an unsatisfactory condition assessment and a moderate risk level. The dam features an uncontrolled spillway with a width of 2 feet and no outlet gates. The Bureau of Land Management is responsible for the design, construction, regulation, and inspection of this dam, ensuring its compliance with state jurisdiction and permitting requirements. With Liz Cheney as the congressional representative for the area, Three Forks Dam plays a crucial role in managing water resources and mitigating potential risks in the region.

Year Completed

1954

Dam Length

270

River Or Stream

MIKE WASH

Primary Dam Type

Gravity

Surface Area

3.4

Hydraulic Height

29

Nid Storage

29.8

Structural Height

36

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

36
       
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.