Dry Muddy Reservoir Report

Last Updated: December 14, 2025

Dry Muddy is a private earth dam located in the Big Muddy Oil Field in Natrona County, Wyoming.


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Summary

Completed in 1933 for irrigation purposes, the dam stands at 19 feet high with a hydraulic height of 14 feet and a length of 800 feet. Despite its age, the dam has a low hazard potential but is in poor condition, as noted during the last inspection in August 2021.

The dam has a normal storage capacity of 213 acre-feet and a maximum storage of 401 acre-feet, serving as a vital water resource for the area. Its spillway type is uncontrolled with a width of 25 feet, and it is equipped with a single valve outlet gate for water release. Although Dry Muddy Creek is the primary source of water for the dam, its drainage area is listed as zero, suggesting potential limitations on its water supply.

With a moderate risk assessment rating, it is crucial for the owner to address the poor condition of Dry Muddy dam to ensure its continued safety and functionality for irrigation purposes. Regular inspections and maintenance are essential to mitigate any potential risks and safeguard this valuable water resource in Wyoming.

Year Completed

1933

Dam Length

800

Dam Height

19

River Or Stream

DRY MUDDY CREEK

Primary Dam Type

Earth

Surface Area

32

Hydraulic Height

14

Nid Storage

401

Structural Height

19

Outlet Gates

Valve - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

19
       
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.