Round Mountain Detention Dam 1 Reservoir Report
Last Updated: December 14, 2025
Located in Franklin, Arizona, Round Mountain Detention Dam 1, also known as Big Tank Detention Dam, was completed in 1954 by the Bureau of Land Management to primarily reduce flood risks in the area.
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Summary
This gravity dam stands at a structural height of 22 feet and has a hydraulic height of 12 feet, with a length of 2109 feet. It has a normal storage capacity of 48.6 acre-feet and a maximum storage capacity of 116 acre-feet, providing vital flood protection for the surrounding Greenlee County.
With a low hazard potential and fair condition assessment, Round Mountain Detention Dam 1 serves as a crucial infrastructure for flood risk reduction along the Round Mountain Draw. The dam's uncontrolled spillway, with a width of 2 feet, can handle a maximum discharge of 4424 cubic feet per second. Despite not being regulated by the state, the dam remains a key asset in mitigating potential flood risks in the region. For water resource and climate enthusiasts, Round Mountain Detention Dam 1 stands as a testament to the Bureau of Land Management's commitment to safeguarding communities from natural disasters through strategic infrastructure development.
Year Completed |
1954 |
Dam Length |
2109 |
River Or Stream |
ROUND MOUNTAIN DRAW |
Primary Dam Type |
Gravity |
Surface Area |
29.1 |
Hydraulic Height |
12 |
Drainage Area |
19.3 |
Nid Storage |
116 |
Structural Height |
22 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
22 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Gila River At Duncan
|
29cfs |
Gila River Below Blue Creek
|
59cfs |
Gila River Near Redrock
|
68cfs |
Gila River At Head Of Safford Valley
|
74cfs |
Gila River Near Clifton
|
45cfs |
Bonita Creek Near Morenci
|
3cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Round Mountain Detention Dam 1