Napili 2-3 Desilting Basin Reservoir Report
Last Updated: December 19, 2025
Napili 2-3 Desilting Basin, also known as Structure #1, is a vital flood risk reduction infrastructure situated 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 desilting basin was designed by the USDA NRCS and completed in 1988. With a dam height of 39 feet and a hydraulic height of 40 feet, the basin serves the primary purpose of flood risk reduction for the NAPILI 2-3 river or stream, covering a drainage area of 0.46 square miles.
This earth dam structure has a structural height of 43 feet and a length of 660 feet, with a storage capacity of 57 acre-feet. The basin's spillway type is uncontrolled, with a width of 12 feet, allowing for a maximum discharge of 1030 cubic feet per second. Despite being classified as having a high hazard potential, the condition assessment of the desilting basin is currently rated as fair. Regular inspections are conducted, with the last one completed in March 2021, ensuring its operational readiness and effectiveness in mitigating flood risks for the surrounding area.
Enthusiasts of water resource management and climate resilience will find the Napili 2-3 Desilting Basin an intriguing case study in flood risk reduction infrastructure. Its strategic location in Napili, Maui, along with its significant storage capacity and controlled discharge capabilities, make it a critical asset in managing flood events in the area. The basin's fair condition assessment and regular inspections reflect a commitment to maintaining its operational integrity and safeguarding the community from potential flood hazards. With its design by the USDA NRCS and state regulation by the DLNR, this desilting basin stands as a testament to collaborative efforts in ensuring water resource sustainability and climate resilience in Hawaii.
Year Completed |
1988 |
Dam Length |
660 |
Dam Height |
39 |
River Or Stream |
NAPILI 2-3 |
Primary Dam Type |
Earth |
Surface Area |
2.1 |
Hydraulic Height |
40 |
Drainage Area |
0.46 |
Nid Storage |
57 |
Structural Height |
43 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
High |
Foundations |
Unlisted/Unknown |
Nid Height |
43 |
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 2-3 Desilting Basin