Flat Reservoir Report

Last Updated: December 8, 2025

Flat is a privately owned irrigation dam located in Campbell County, Wyoming, along Flat Creek.


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Summary

Built in 1914, this earth dam stands at 10 feet tall and spans 1200 feet in length, with a maximum storage capacity of 149 acre-feet. The dam is regulated by the Wyoming State Engineer's Office and undergoes regular inspections to ensure its fair condition and low hazard potential.

Despite its age, the dam's risk assessment is moderate, indicating a level 3 risk. It features an uncontrolled spillway with a width of 300 feet and a single valve outlet gate. While the dam has not been modified or updated in recent years, its emergency action plan status and inundation maps are unknown. Overall, Flat serves an essential purpose for irrigation in the region and remains a key structure in the local water resource management system.

Year Completed

1914

Dam Length

1200

Dam Height

10

River Or Stream

FLAT CREEK

Primary Dam Type

Earth

Surface Area

48

Hydraulic Height

5

Nid Storage

149

Structural Height

10

Outlet Gates

Valve - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

10
       
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.