Helemano 6 Reservoir Reservoir Report
Last Updated: December 19, 2025
Helemano 6 Reservoir, located in Honolulu, Hawaii, was completed in 1915 and serves a primary purpose of irrigation.
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Summary
This private reservoir stands at a structural height of 38 feet, with a dam height of 36 feet and a hydraulic height of 30 feet. It has a storage capacity of 80 acre-feet, with a normal storage level of 66 acre-feet and a surface area of 4.6 acres. The reservoir is situated near the North Pomoho Stream, making it a vital water resource for the surrounding area.
Despite its age, Helemano 6 Reservoir is in poor condition with a high hazard potential, as indicated by its last inspection in 2020. The spillway type is uncontrolled with a width of 10 feet, and the dam is classified as an earth dam with a buttress core type. The reservoir is regulated by the Department of Land and Natural Resources (DLNR) in Hawaii, with state jurisdiction and permitting in place. The risk assessment for the reservoir is moderate, highlighting the importance of ongoing maintenance and management measures to ensure its safety and functionality for irrigation purposes.
In light of its historical significance and critical role in providing irrigation water, Helemano 6 Reservoir stands as a testament to the enduring importance of water resources in the face of climate challenges. As efforts continue to assess and address the reservoir's condition and safety, its value as a sustainable water source in Honolulu, Hawaii, remains paramount for the local community and agricultural operations in the region.
Year Completed |
1915 |
Dam Length |
250 |
Dam Height |
36 |
River Or Stream |
NORTH POMOHO STREAM |
Primary Dam Type |
Earth |
Surface Area |
4.6 |
Hydraulic Height |
30 |
Drainage Area |
1.3 |
Nid Storage |
80 |
Structural Height |
38 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
38 |
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 |
Makaha Str Nr Makaha
|
16cfs |
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 Mokuleia
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Malaekahana State Rec Area - Oahu
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Malaekahana Beach Campground
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Kea'au Beach Park
|
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Kahana Valley State Park - Oahu
|
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Kahana campground
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Helemano 6 Reservoir