Massae Reservoir Report

Last Updated: December 4, 2025

Massae, a privately owned dam located in Uinta, Wyoming, serves the primary purpose of irrigation along the Mill Creek offstream.


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Summary

Constructed in 1968 by designer JOHN A PROFFIT, this earth dam stands at 24 feet high with a hydraulic height of 19 feet, providing a storage capacity of 266 acre-feet. Despite its low hazard potential, the dam's condition assessment is rated as poor, last inspected in July 2019.

With a spillway width of 24 feet and an outlet gate controlled by a single valve, Massae's risk assessment categorizes it as moderate. The dam's overall risk management measures and preparedness for emergencies, such as the creation of an Emergency Action Plan (EAP), remain unspecified. As the dam is regulated by the Wyoming State Engineer's Office and is subject to periodic inspections and enforcement, its role in water resource management in the region is vital.

In the context of the changing climate and increasing pressure on water resources, the maintenance and monitoring of dams like Massae are crucial for ensuring water security and mitigating potential risks. The coordination between private owners, state agencies, and federal representatives, such as Liz Cheney, is essential for the sustainable management of water infrastructure and the protection of communities downstream.

Year Completed

1968

Dam Length

3142

Dam Height

24

River Or Stream

MILL CREEK OFFSTREAM

Primary Dam Type

Earth

Surface Area

22

Hydraulic Height

19

Nid Storage

266

Structural Height

24

Outlet Gates

Valve - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

24
       
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.