One Eleven Detention Dam Reservoir Report

Last Updated: December 26, 2025

One Eleven Detention Dam, located in Solomon, Arizona, along the San Simon River, is a gravity dam primarily designed for flood risk reduction.


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Summary

Built in 1968 by the Bureau of Land Management, this federal structure stands 37 feet tall with a hydraulic height of 34 feet and a length of 850 feet. It has a storage capacity of 657.9 acre-feet, with a normal storage level of 448.5 acre-feet, covering a surface area of 42.4 acres and serving a drainage area of 14.8 square miles.

Despite its low hazard potential and fair condition assessment, the dam has not been inspected since July 2009. However, it has an inspection frequency of 5 years and appears to be well-maintained by the Bureau of Land Management. The dam features an uncontrolled spillway with a width of 24 feet, capable of handling a maximum discharge of 1488 cubic feet per second. With a moderate risk assessment rating of 3, there is a need for updated emergency action plans and risk management measures to ensure the safety and functionality of this essential water resource infrastructure.

Overall, One Eleven Detention Dam plays a vital role in protecting the surrounding areas from flood risks, showcasing a successful collaboration between federal agencies and the local community. As climate change continues to impact water resources, it is crucial to prioritize the maintenance and inspection of such structures to mitigate potential hazards and ensure the sustainable management of water infrastructure for future generations.

Year Completed

1968

Dam Length

850

River Or Stream

SAN SIMON RIVER

Primary Dam Type

Gravity

Surface Area

42.4

Hydraulic Height

34

Drainage Area

14.8

Nid Storage

657.9

Structural Height

37

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

37
       
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.