Opaeula 01 Reservoir Reservoir Report
Last Updated: December 19, 2025
Opaeula 01 Reservoir, located in Honolulu, Hawaii, was completed in 1910 and serves as a vital irrigation source in the region.
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Summary
The dam stands at 66 feet high, with a hydraulic height of 60 feet, and a structural height of 71 feet. With a storage capacity of 320 acre-feet, the reservoir covers a surface area of 9.7 acres and has a drainage area of 0.23 square miles. Despite its age, the dam is in fair condition and is inspected every 5 years to ensure its safety and functionality.
Managed by a private entity, the Opaeula 01 Reservoir is regulated by the State of Hawaii's Department of Land and Natural Resources (DLNR) and is subject to state permitting, inspection, and enforcement measures. The dam's spillway type is uncontrolled, with a width of 16 feet, and it poses a high hazard potential. The reservoir's primary purpose is irrigation, and it plays a crucial role in supporting agricultural activities in the area. With a moderate risk assessment rating of 3, the dam is closely monitored to mitigate potential risks and ensure the safety of surrounding communities.
In the event of an emergency, the dam has an emergency action plan (EAP) in place, although its last revision date was in October 2019. While the risk management measures and inundation maps may need updating, the reservoir continues to provide essential water resources for the region. The Opaeula 01 Reservoir stands as a testament to the importance of proper dam maintenance and oversight in safeguarding water supplies and mitigating potential risks associated with aging infrastructure in a changing climate.
Year Completed |
1910 |
Dam Length |
250 |
Dam Height |
66 |
River Or Stream |
TR-ANAHULU RIVER |
Primary Dam Type |
Earth |
Surface Area |
9.7 |
Hydraulic Height |
60 |
Drainage Area |
0.23 |
Nid Storage |
320 |
Structural Height |
71 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
71 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Opaeula Str Nr Wahiawa
|
27cfs |
Kamananui Str At Pupukea Mil Rd
|
15cfs |
Kamananui Str At Maunawai
|
84cfs |
Sf Kaukonahua Str At E Pump
|
34cfs |
Nf Kaukonahua Str Abv Rb
|
13cfs |
Kaluanui Stream Nr Punaluu
|
2cfs |
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 |
|---|---|---|
Malaekahana State Rec Area - Oahu
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Malaekahana Beach Campground
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Kahana Valley State Park - Oahu
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Kahana campground
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Camp Mokuleia
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Opaeula 01 Reservoir