Oahu Reservoir 155
Oahu Reservoir 155 is an earth dam located in Honolulu County, Hawaii, built in 1916. It carries a High hazard potential classification and has a poor condition assessment.
About Oahu Reservoir 155
The primary purpose of Oahu Reservoir 155 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Agribusiness Development Corporation (adc), Bayer U.s. - Crop Science, Monsanto Company, Monsanto Company (state).
The dam stands 25 feet tall and stretches 900 feet across, creates a reservoir covering 2 acres, and has a maximum storage capacity of 37 acre-feet. Completed in 1916, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. An emergency action plan is in place for this dam. The most recent inspection on record was 03/15/2025.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Hawaii dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Hawaii |
| County | Honolulu |
| Nearest City | Waipahu |
| Coordinates | 21.40462, -158.05933 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 900 ft |
| Year Completed | 1916 (110 years old) |
Storage & Hydraulics
| NID Storage | 37 acre-ft |
| Max Storage | 37 acre-ft |
| Surface Area | 2 acres |
| Max Discharge | 110 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Agribusiness Development Corporation (ADC), Bayer U.S. - Crop Science, Monsanto Company, Monsanto Company |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 03/15/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | HI00137 |
| Federal ID | HI00137 |
| More Info | State Dam Safety Program |