Mauka Reservoir
Mauka Reservoir is an earth dam located in Kauai County, Hawaii, built in 1910. It carries a High hazard potential classification and has a poor condition assessment.
About Mauka Reservoir
The primary purpose of Mauka Reservoir is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Eric A. Knudsen Trust (private). It impounds the Waihohonu Stream near Koloa.
The dam stands 19 feet tall and stretches 550 feet across, creates a reservoir covering 23 acres, has a maximum storage capacity of 345 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1910, 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 01/29/2026.
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 | Kauai |
| Nearest City | Koloa |
| River/Stream | Waihohonu Stream |
| Coordinates | 21.94139, -159.46897 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 19 ft |
| Dam Height | 19 ft |
| Dam Length | 550 ft |
| Year Completed | 1910 (116 years old) |
Storage & Hydraulics
| NID Storage | 345 acre-ft |
| Max Storage | 345 acre-ft |
| Normal Storage | 110 acre-ft |
| Surface Area | 23 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 2,193 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Eric A. Knudsen Trust |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 01/29/2026 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | HI00119 |
| Federal ID | HI00119 |
| More Info | State Dam Safety Program |