Napili 4-5 Desilting Basin Reservoir Report
Last Updated: December 19, 2025
Napili 4-5 Desilting Basin, also known as Structure#2, is a vital flood risk reduction infrastructure located in Napili, Maui, Hawaii.
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Summary
Owned by the local government and regulated by the Department of Land and Natural Resources (DLNR), this Earth-type dam stands at a height of 18 feet and stretches 270 feet in length. Completed in 1985 and designed by the USDA NRCS, the basin serves the primary purpose of flood risk reduction for the Napili 4-5 river/stream, with a maximum discharge capacity of 1600 cubic feet per second.
With a hazard potential rated as high and a fair condition assessment in 2021, the Napili 4-5 Desilting Basin plays a crucial role in managing water resources in the region. The dam has a storage capacity of 25 acre-feet and covers a surface area of 2.2 acres, serving a drainage area of 0.93 square miles. Despite its age, the structure continues to be inspected and regulated by state authorities, ensuring its operational effectiveness in mitigating flood risks in the area.
This desilting basin, situated in a picturesque location in Maui, not only contributes to flood control but also highlights the importance of sustainable water resource management in the face of changing climate patterns. As climate enthusiasts and water resource stakeholders monitor its performance and condition, the Napili 4-5 Desilting Basin stands as a testament to the ongoing efforts to safeguard communities and ecosystems from the impacts of extreme weather events and water-related disasters.
Year Completed |
1985 |
Dam Length |
270 |
Dam Height |
14 |
River Or Stream |
NAPILI 4-5 |
Primary Dam Type |
Earth |
Surface Area |
2.2 |
Hydraulic Height |
18 |
Drainage Area |
0.93 |
Nid Storage |
25 |
Structural Height |
18 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
18 |
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.
Napili 4-5 Desilting Basin