Big Supai Tank Reservoir Report
Nearby: Mclellan West Cataract Creek
Last Updated: December 5, 2025
Big Supai Tank, located in Coconino, Arizona, is a privately owned earth dam completed in 1882 to store water from Johnson Creek.
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Summary
With a height of 34.4 feet and a storage capacity of 55.5 acre-feet, this historic structure serves as a vital resource in the region. Despite being unregulated by federal agencies, the Arizona Department of Water Resources oversees its permitting, inspection, and enforcement to ensure its safety and functionality.
This low-hazard dam, with a surface area of 8.6 acres and a drainage area of 2.18 square miles, plays a crucial role in water management in the area. Although not rated for its condition assessment, the dam has a high risk assessment due to its age and historical significance. Regular inspections, last conducted in October 2018, help monitor its integrity and mitigate potential risks. Its location in the scenic surroundings of S34, T22N, R1E adds to its allure for water resource and climate enthusiasts interested in the intersection of history, engineering, and natural landscapes.
As one of the oldest dams in the region, Big Supai Tank stands as a testament to early water management practices and the importance of preserving such heritage structures. Its role in storing water for agricultural and other purposes highlights the need for continued monitoring and maintenance to ensure its longevity and functionality. For enthusiasts interested in the intersection of water resources, climate, and historical infrastructure, this site offers a fascinating glimpse into the past while also raising questions about the future of water management in a changing climate.
Year Completed |
1882 |
Dam Length |
790 |
Dam Height |
34.4 |
River Or Stream |
JOHNSON CREEK |
Primary Dam Type |
Earth |
Surface Area |
8.6 |
Hydraulic Height |
34.4 |
Drainage Area |
2.18 |
Nid Storage |
55.5 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
34 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Kaibab Lake Campground
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Kaibab Lake
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Kaibab Lake Campground and Group Areas
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Dogtown Lake
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Dogtown Lake Campground
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Big Supai Tank