Shell Creek Reservoir Report

Last Updated: December 5, 2025

Shell Creek, located in Big Horn, Wyoming, is a privately owned earth dam completed in 1957 for irrigation purposes.


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Summary

With a height of 40 feet and a hydraulic height of 33 feet, the dam has a storage capacity of 2680 acre-feet, serving a drainage area of 24 square miles. The spillway, an uncontrolled type, has a width of 214 feet, allowing for a maximum discharge of 1800 cubic feet per second.

Despite its high hazard potential and moderate risk assessment, Shell Creek has been deemed to meet regulatory guidelines and undergoes regular inspections every 5 years. The dam is managed by the Wyoming State Engineer's Office and is in a state of satisfactory condition as of the last assessment in July 2020. The surrounding area, situated in the city of Shell, benefits from the water resource provided by Shell Creek for agricultural purposes, highlighting the importance of maintaining this vital infrastructure for the local community and ecosystem.

Year Completed

1957

Dam Length

400

Dam Height

40

River Or Stream

SHELL CREEK

Primary Dam Type

Earth

Surface Area

98

Hydraulic Height

33

Drainage Area

24

Nid Storage

2680

Structural Height

50

Outlet Gates

Uncontrolled - 2

Hazard Potential

High

Foundations

Soil

Nid Height

50
       
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.