Mcninch No. 1 Reservoir Report

Last Updated: December 13, 2025

Mcninch No.


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Summary

1, also known as Enl of 5413r, is a private irrigation dam located in Sublette, Wyoming, specifically in the city of Big Piney. Built in 1947, this earth dam stands at a height of 33 feet with a hydraulic height of 28 feet, serving the primary purpose of irrigation. The dam boasts a storage capacity of 1,620 acre-feet, with a normal storage capacity of 1,086 acre-feet across its 1.5 square mile drainage area.

With a low hazard potential and fair condition assessment as of August 2020, this structure has been subject to regular inspections every five years to ensure its operational safety. The dam features an uncontrolled spillway with a width of 18 feet, along with a slide (sluice gate) outlet gate. Despite its moderate risk rating, Mcninch No. 1 remains a vital asset for water resource management in the region, highlighting the importance of maintaining and monitoring such essential infrastructure.

Year Completed

1947

Dam Length

1150

Dam Height

33

River Or Stream

BEAVER CREEK OFFSTREAM

Primary Dam Type

Earth

Surface Area

107

Hydraulic Height

28

Drainage Area

1.5

Nid Storage

1620

Structural Height

33

Outlet Gates

Slide (sluice gate) - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

33
       
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.