Nuuanu Reservoir No. 1 Reservoir Report
Nearby: Nuuanu Dam No. 4 Kaneohe Dam
Last Updated: December 19, 2025
Nuuanu Reservoir No.
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Summary
1, located in Honolulu, Hawaii, has been a vital water resource for the local government since its completion in 1905. With a capacity of 63.5 million gallons and a normal storage level of 44 million gallons, this earth dam structure plays a crucial role in water supply management for the region. The reservoir covers a surface area of 6.2 acres and has a drainage area of 0.13 square miles, highlighting its significance in the local hydrological system.
Despite its historical importance, Nuuanu Reservoir No. 1 has faced challenges in recent years, with a poor condition assessment in 2014 and a high hazard potential. The dam's last inspection in February 2021 revealed the need for frequent monitoring and maintenance, with a 5-year inspection frequency in place. The reservoir's spillway type is uncontrolled, with a width of 3 feet, posing additional risks in cases of excessive water inflow. As climate change impacts water resources, the resilience and management of structures like Nuuanu Reservoir No. 1 become increasingly crucial for sustainable water supply and disaster mitigation in the region.
Efforts to address the dam's condition and safety concerns are ongoing, with a risk assessment rating it as moderate. With the potential hazards in mind, stakeholders must prioritize risk management measures and emergency preparedness to ensure the continued functionality and safety of Nuuanu Reservoir No. 1. As water resource and climate enthusiasts, staying informed and involved in the maintenance and regulation of critical infrastructure like this reservoir is essential for safeguarding water security and adapting to changing environmental conditions.
Year Completed |
1905 |
Dam Length |
588 |
Dam Height |
33.5 |
Primary Dam Type |
Earth |
Surface Area |
6.2 |
Drainage Area |
0.13 |
Nid Storage |
63.5 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
34 |
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 |
|---|---|---|
Sand Island State Rec Area - Oahu
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Keaiwa Heiau State Rec Area - Oahu
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Kulamanu Beach
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Bellows Field Beach Park - Oahu
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Waimanalo beach park
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Nuuanu Reservoir No. 1