Maui Reservoir 21 Reservoir Report
Nearby: Maui Reservoir 24 Maui Reservoir 22
Last Updated: December 19, 2025
Maui Reservoir 21, also known as Hc&S Reservoir 21, is a privately owned water storage facility located in Upper Paia, Maui, Hawaii.
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Summary
Completed in 1913, this earth dam stands at a height of 22 feet and has a storage capacity of 72.4 million gallons, primarily used for irrigation purposes. The reservoir covers a surface area of 6.9 acres and is fed by the Irrigation Gulch, serving as a vital resource for the surrounding agricultural lands.
Maintained and regulated by the Hawaii Department of Land and Natural Resources, Maui Reservoir 21 has a high hazard potential due to its size and location. Despite its age, the dam is in fair condition and undergoes regular inspections to ensure its structural integrity. With a moderate risk assessment rating, the reservoir plays a crucial role in water management in the region, supporting the local farming community and contributing to the sustainability of the area's water resources.
Situated within the Honolulu District and overseen by state authorities, Maui Reservoir 21 serves as a significant component of the water infrastructure in Maui County. With a history dating back over a century, this reservoir remains a key feature of the landscape, highlighting the importance of water conservation and management in the face of changing climate patterns. For water resource and climate enthusiasts, Maui Reservoir 21 offers a glimpse into the intersection of history, technology, and environmental stewardship in the Hawaiian Islands.
Year Completed |
1913 |
Dam Length |
950 |
Dam Height |
22 |
River Or Stream |
FED BY IRRIGATION GULCH |
Primary Dam Type |
Earth |
Surface Area |
6.9 |
Hydraulic Height |
16 |
Drainage Area |
0.03 |
Nid Storage |
72.4 |
Structural Height |
18 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
22 |
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.
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Maui Reservoir 21