Magleby Reservoir Report

Last Updated: December 5, 2025

Magleby is a privately owned dam located in Sevier County, Utah, along Monroe Creek.


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Summary

Completed in 1915, this Earth-type dam serves primarily for irrigation purposes, with a storage capacity of 80 acre-feet. The dam stands at a structural height of 18 feet, with a hydraulic height of 16 feet, and a length of 305 feet. Despite not having a hazard potential rating or condition assessment, the Utah Division of Water Rights regulates and inspects Magleby regularly to ensure its safety and compliance.

Situated in the city of Greenwich, Magleby is a significant water resource in the region, supporting agricultural activities and water distribution. Being state-regulated and permitted, the dam undergoes inspections every two years, with the last one conducted in July 2020. Its location within the Los Angeles District and under the jurisdiction of the Utah Division of Water Rights highlights the importance of maintaining its structural integrity and functionality to meet the irrigation needs of the area.

With its historical significance dating back over a century, Magleby continues to play a vital role in the water management infrastructure of Sevier County, Utah. As a key component for irrigation purposes, the dam contributes to the sustainability of agricultural practices in the region. Regular inspections and state oversight ensure the safety and reliability of Magleby, reinforcing its importance in water resource management and climate resilience efforts in the area.

Year Completed

1915

Dam Length

305

River Or Stream

MONROE CREEK

Primary Dam Type

Earth

Hydraulic Height

16

Drainage Area

2

Nid Storage

80

Structural Height

18

Hazard Potential

Significant

Nid Height

18
       
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.