Peahi Reservoir Reservoir Report
Last Updated: December 20, 2025
Peahi Reservoir, located in Ulumalu, Maui, Hawaii, is a privately owned irrigation structure completed in 1924 with a primary purpose of irrigation.
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Summary
The reservoir, with a height of 45 feet and a capacity of 72 acre-feet, serves as a critical water resource for the surrounding area, storing up to 66 acre-feet of water under normal conditions. The dam, of earth type with a buttress core, spans 170 feet in length and covers a surface area of 5.8 acres, drawing water from the Uaoa Stream for agricultural use.
Despite its essential role in supporting local agriculture, Peahi Reservoir poses a high hazard potential with a poor condition assessment, indicating the need for immediate attention and maintenance. The dam's spillway, of uncontrolled type, features a width of 32 feet to manage excess water flow during heavy rainfall events. While the structure has been inspected periodically, the last assessment in December 2018 revealed significant issues, prompting a risk assessment rating of moderate (3) and highlighting the importance of implementing effective risk management measures to ensure the safety and stability of the reservoir.
As climate change continues to impact water resources and infrastructure, Peahi Reservoir stands as a vital yet vulnerable asset in need of ongoing monitoring and maintenance. With its strategic location in the Honolulu District and close proximity to the Uaoa Stream, the reservoir plays a crucial role in sustaining local agriculture and community livelihoods, underscoring the importance of proactive management and investment in safeguarding water resources for future generations.
Year Completed |
1924 |
Dam Length |
170 |
Dam Height |
35 |
River Or Stream |
UAOA STREAM |
Primary Dam Type |
Earth |
Surface Area |
5.8 |
Hydraulic Height |
40 |
Drainage Area |
0.78 |
Nid Storage |
72 |
Structural Height |
45 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
45 |
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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Peahi Reservoir