Horner Reservoir Reservoir Report
Nearby: Hanakaoo Reservoir Reservoir 140
Last Updated: December 18, 2025
Horner Reservoir is a privately-owned water storage facility located in Maui, Hawaii, with a primary purpose of irrigation.
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Summary
Built in 1926, this earth dam structure stands at a height of 70 feet and has a storage capacity of 88 acre-feet. The reservoir covers a surface area of 5.9 acres and is fed by an irrigation ditch, serving as a vital source of water for agricultural activities in the region.
Despite its historical significance, Horner Reservoir faces challenges in terms of its condition assessment, which is rated as poor, and its hazard potential is classified as high. The last inspection in December 2018 revealed the dam's deteriorating state, prompting the need for immediate attention to ensure public safety and efficient water resource management. With a moderate risk assessment score of 3, there is a pressing need for risk management measures to be implemented to address potential safety concerns and prevent any adverse environmental impacts.
As a key water resource structure in Maui, Horner Reservoir plays a crucial role in supporting the local agricultural industry. However, its deteriorating condition and high hazard potential underscore the importance of ongoing maintenance and monitoring efforts to safeguard its integrity and ensure sustainable water management practices. Climate enthusiasts and water resource professionals alike are urged to stay informed about the challenges facing Horner Reservoir and advocate for proactive measures to protect this vital resource for future generations.
Year Completed |
1926 |
Dam Length |
1100 |
Dam Height |
70 |
River Or Stream |
FED BY IRRIGATION DITCH |
Primary Dam Type |
Earth |
Surface Area |
5.9 |
Hydraulic Height |
34 |
Drainage Area |
0.06 |
Nid Storage |
88 |
Structural Height |
37 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
70 |
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 |
|---|---|---|
Camp Olowalu - Maui
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Camp Olowalu
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papalau camping
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Horner Reservoir