Map of All 125 Hawaii Dams
Hawaii has 125 dams in the National Inventory of Dams — and 118 are classified as high hazard (94% of the state’s total), meaning failure would likely cause loss of life. 88 Hawaii dams are both high-hazard and in poor or unsatisfactory condition.
Use the interactive Hawaii dams map below to explore every dam in the state, color-coded by hazard level. Click any dam for its condition assessment, last inspection date, and Emergency Action Plan status. Or view the full US Dams interactive map to compare Hawaii to every other state.
Hazard
Condition
Purpose
Hawaii Dams by the Numbers
- 125 total dams in Hawaii
- 118 high hazard — failure would likely cause loss of life
- 2 significant hazard
- 5 low hazard
- 95 in poor or unsatisfactory condition (79 poor, 16 unsatisfactory)
- 88 Hawaii dams are both high-hazard AND in poor/unsatisfactory condition
Data source: US Army Corps of Engineers, National Inventory of Dams (NID).
The Tallest Dams in Hawaii
The tallest dam in Hawaii is Alexander at 141 feet, completed in 1931. The 10 tallest Hawaii dams from the National Inventory of Dams:
| Dam | Height | Year | Primary Purpose | Condition | County |
|---|---|---|---|---|---|
| Alexander | 141 ft | 1931 | Hydroelectric | Fair | Kauai |
| Puu Lua Reservoir | 110 ft | 1925 | Fish and Wildlife Pond | Unsatisfactory | Kauai |
| Wahiawa Dam | 98 ft | 1906 | Irrigation | Poor | Honolulu |
| Ku Tree Reservoir | 90 ft | 1925 | Other | Unsatisfactory | Honolulu |
| Kaneohe Dam | 83 ft | 1980 | Flood Risk Reduction | Fair | Honolulu |
| Aepo Reservoir | 74 ft | 1901 | Irrigation | Fair | Kauai |
| Nuuanu Dam No. 4 | 73 ft | 1910 | Flood Risk Reduction | Fair | Honolulu |
| Opaeula 01 Reservoir | 71 ft | 1910 | Irrigation | Fair | Honolulu |
| Horner Reservoir | 70 ft | 1926 | Irrigation | Poor | Maui |
| Koolau Reservoir | 70 ft | 1919 | Other | Unsatisfactory | Honolulu |
High-Hazard Hawaii Dams in Poor Condition
The most concerning dams are those classified as high-hazard that also carry a Poor or Unsatisfactory condition rating — 88 dams in Hawaii. Notable examples:
- Puu Lua Reservoir (110 ft, Kauai County) — Fish and Wildlife Pond, Unsatisfactory condition
- Wahiawa Dam (98 ft, Honolulu County) — Irrigation, Poor condition
- Ku Tree Reservoir (90 ft, Honolulu County) — Other, Unsatisfactory condition
- Horner Reservoir (70 ft, Maui County) — Irrigation, Poor condition
- Mimino Reservoir (69 ft, Kauai County) — Irrigation, Poor condition
Filter the interactive US Dams map by hazard and condition to see all of them on one view.
Dam Safety in Hawaii
Dam safety in Hawaii is overseen by the state dam safety program, in coordination with federal regulators: the US Army Corps of Engineers, the Bureau of Reclamation (for federal water projects), the Tennessee Valley Authority where applicable, and the Federal Energy Regulatory Commission (FERC) for licensed hydropower dams. Emergency Action Plans are typically required for high-hazard dams under state regulations.
Frequently Asked Questions
How many dams are in Hawaii?
Hawaii has 125 dams in the National Inventory of Dams tracked by the US Army Corps of Engineers: 118 high hazard, 2 significant hazard, and 5 low hazard.
What is the tallest dam in Hawaii?
The tallest dam in Hawaii is Alexander at 141 feet, completed in 1931. It is primarily a hydroelectric structure.
How many Hawaii dams are in poor condition?
95 Hawaii dams are currently rated as being in Poor or Unsatisfactory condition. Of those, 88 are also classified as high-hazard — meaning failure would likely cause loss of life.
