Waikoloa Reservoir No. 1 Reservoir Report
Last Updated: December 24, 2025
Waikoloa Reservoir No.
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Summary
1, also known as Waikoloa 50 Mg Reservoir 1, is a significant water supply structure located in Waimea, Hawaii. Constructed in 1970, this earth dam stands at a height of 44 feet and has a storage capacity of 190 acre-feet, with a normal storage level of 157 acre-feet. The reservoir covers a surface area of 6.7 acres and is primarily used for water supply purposes.
Managed by the Hawaii Department of Land and Natural Resources (DLNR), Waikoloa Reservoir No. 1 is regulated by the state and undergoes regular inspections to ensure its safety and functionality. Despite its high hazard potential and poor condition assessment, the dam continues to serve as a crucial water resource for the local community. With a spillway width of 14 feet and a maximum discharge of 160 cubic feet per second, the reservoir plays a vital role in managing water resources in the region.
Although facing moderate risks, Waikoloa Reservoir No. 1 remains an essential infrastructure for water supply in Hawaii. With ongoing risk management measures and inspection protocols in place, the dam continues to support the local environment and community, highlighting the importance of sustainable water resource management in the face of climate challenges.
Year Completed |
1970 |
Dam Length |
1700 |
Dam Height |
44 |
River Or Stream |
WAIKOLOA-OFFSTREAM |
Primary Dam Type |
Earth |
Surface Area |
6.7 |
Hydraulic Height |
40 |
Nid Storage |
190 |
Structural Height |
40 |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
44 |
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. 1