Omao Reservoir Reservoir Report
Nearby: Pia Mill Reservoir Aepo Reservoir
Last Updated: December 19, 2025
Located in Koloa, Hawaii, the Omao Reservoir stands as a vital water resource for irrigation purposes since its completion in 1915.
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Summary
With a dam height of 40 feet and a storage capacity of 194 acre-feet, this earth dam on the Omao Stream serves as a key infrastructure for agricultural activities in the region. Despite its high hazard potential and poor condition assessment, the reservoir continues to play a crucial role in water management and agriculture in the area.
Managed by private owners and regulated by the Hawaii Department of Land and Natural Resources, the Omao Reservoir is equipped with an uncontrolled spillway and has a maximum discharge capacity of 3000 cubic feet per second. The reservoir covers a surface area of 8.5 acres and has a drainage area of 1.17 square miles, making it a significant water storage facility in the region. Although facing moderate risk due to its condition, the reservoir remains a cornerstone for water supply and irrigation in Kauai, Hawaii.
As climate change impacts water resources worldwide, the Omao Reservoir stands as a crucial piece of infrastructure to ensure sustainable water management in the region. With ongoing inspections and enforcement measures in place, efforts are being made to address the reservoir's poor condition and high hazard potential. As water resource and climate enthusiasts, it is essential to monitor and support initiatives that aim to preserve and enhance vital water storage facilities like the Omao Reservoir for a more resilient and sustainable future.
Year Completed |
1915 |
Dam Length |
454 |
Dam Height |
40 |
River Or Stream |
OMAO STREAM |
Primary Dam Type |
Earth |
Surface Area |
8.5 |
Hydraulic Height |
30 |
Drainage Area |
1.17 |
Nid Storage |
194 |
Structural Height |
35 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
40 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Sf Wailua River Nr Lihue
|
173cfs |
Eb Of Nf Wailua River Nr Lihue
|
39cfs |
Left Branch Opaekaa Str Nr Kapaa
|
2cfs |
Waimea River Nr Waimea
|
295cfs |
Waialae Str At Alt 3
|
34cfs |
Wainiha River Nr Hanalei
|
178cfs |
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
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Niumalu Park - Kauai
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Hanamaulu Beach Park - Kauai
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Lucy Wright Beach Park - Kauai
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Omao Reservoir