28 Tank Reservoir Report
Nearby: Canyon Mouth Railroad Embankment
Last Updated: December 15, 2025
28 Tank, located in Supai Village, Yavapai County, Arizona, is a private water resource managed by the Arizona Department of Water Resources.
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Summary
Built in 1909, this earth dam stands at 32.5 feet high and serves multiple purposes including fire protection, stock watering, and small fish pond maintenance. With a storage capacity of 181.8 acre-feet and a surface area of 16.78 acres, 28 Tank plays a crucial role in water management in the region.
The dam's spillway, measuring 64 feet wide, is uncontrolled, and the hazard potential is classified as low with a moderate risk assessment rating. Although the condition assessment is not rated, regular inspections are conducted every 5 years, with the last inspection taking place in April 2012. The primary owner of 28 Tank is a private entity, and the water source, Spring Valley Wash, supports the surrounding ecosystem and provides essential resources for both wildlife and human consumption.
Overall, 28 Tank is a vital water resource in the area, ensuring water availability for various purposes while also managing the risk associated with its infrastructure. As climate change continues to impact water resources, the proper maintenance and regulation of dams like 28 Tank become increasingly important to sustainably manage water in arid regions like Arizona.
Year Completed |
1909 |
Dam Length |
382 |
Dam Height |
32.5 |
River Or Stream |
SPRING VALLEY WASH |
Primary Dam Type |
Earth |
Surface Area |
16.78 |
Hydraulic Height |
32.5 |
Nid Storage |
181.8 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
33 |
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.
28 Tank