Waikoloa Reservoir No. 2 Reservoir Report
Last Updated: December 24, 2025
Waikoloa Reservoir No.
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Summary
2, also known as Waikoloa 50 Mg Reservoir 2, is a key water resource infrastructure located in Waimea, Hawaii. Completed in 1975, this earth dam stands at a height of 30.5 meters and serves the primary purpose of water supply. With a maximum storage capacity of 190 million gallons and a normal storage of 157 million gallons, this reservoir plays a crucial role in ensuring a reliable water source for the local community.
Situated along the Kohakohau Stream, this reservoir covers a surface area of 7.3 acres and has a drainage area of 0.01 square miles. Despite a high hazard potential due to its structural design, the dam is currently assessed to be in fair condition. Regular inspections are conducted, with the last assessment taking place in March 2020. The reservoir's spillway, with a width of 5 meters, is designed as uncontrolled, allowing for a maximum discharge of 250 cubic feet per second in case of excess water flow.
Managed by the state regulatory agency DLNR, Waikoloa Reservoir No. 2 serves as a vital water supply structure in Hawaii. With its strategic location and significant storage capacity, this reservoir plays a critical role in sustaining water resources for the local community, highlighting the importance of effective management and maintenance of water infrastructure in the face of climate challenges and increasing water demand.
Year Completed |
1975 |
Dam Length |
2000 |
Dam Height |
30.5 |
River Or Stream |
Kohakohau Stream |
Primary Dam Type |
Earth |
Surface Area |
7.3 |
Hydraulic Height |
35 |
Drainage Area |
0.01 |
Nid Storage |
190 |
Structural Height |
35 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
35 |
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.
Waikoloa Reservoir No. 2