Lebanon Reservoir #1 (Upper) Reservoir Report

Last Updated: December 5, 2025

Lebanon Reservoir #1 (Upper) in Arizona, completed in 1910, serves as a vital water resource for irrigation purposes in the region.


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Summary

With a dam height of 40 feet and a storage capacity of 147 acre-feet, this earth dam structure spans 570 feet in length and covers a surface area of 9 acres. Located in Safford, Graham County, this reservoir is regulated by the Arizona Department of Water Resources and undergoes regular inspections to ensure its fair condition and significant hazard potential.

The reservoir is situated on Marijilda Wash - OS and is owned jointly by private and state entities. It features an uncontrolled spillway with a width of 10 feet and a maximum discharge capacity of 210 cubic feet per second. Despite its fair condition, the Lebanon Reservoir #1 (Upper) poses a moderate risk, prompting the need for risk management measures to be implemented. Overall, this reservoir plays a crucial role in supporting the local agricultural community by providing essential water resources for irrigation.

As a key component of the water infrastructure in the area, Lebanon Reservoir #1 (Upper) not only facilitates irrigation activities but also contributes to the overall water management efforts in Arizona. Its historical significance, dating back over a century, underscores its importance in sustaining agricultural operations and ensuring water availability for the region. With a focus on maintaining its structural integrity and addressing any potential risks, this reservoir remains a vital resource for water and climate enthusiasts interested in sustainable water resource management practices.

Year Completed

1910

Dam Length

570

Dam Height

40

River Or Stream

MARIJILDA WASH - OS

Primary Dam Type

Earth

Surface Area

9

Drainage Area

0.5

Nid Storage

147

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

40
       
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.