Largest Reservoirs in Hawaii
Hawaii has 122 dams with recorded storage capacity. The largest is Waita Reservoir with 9,900 acre-feet of maximum storage. One acre-foot equals about 326,000 gallons — enough to supply roughly two households for a year.
| # | Dam | County | Max Storage (acre-ft) | Height (ft) | Purpose | Year |
|---|---|---|---|---|---|---|
| 1 | Waita Reservoir | Kauai | 9,900 | 28 | Irrigation | 1906 |
| 2 | Wahiawa Dam | Honolulu | 9,200 | 98 | Irrigation | 1906 |
| 3 | Kualapuu Reservoir | Maui | 5,082 | 58 | Irrigation | 1969 |
| 4 | Kaneohe Dam | Honolulu | 4,500 | 83 | Flood Risk Reduction | 1980 |
| 5 | Nuuanu Dam No. 4 | Honolulu | 3,600 | 73 | Flood Risk Reduction | 1910 |
| 6 | Alexander | Kauai | 2,777 | 141 | Hydroelectric | 1931 |
| 7 | Puukapu Watershed Retarding Dam R-1 | Hawaii | 1,450 | 12 | Flood Risk Reduction | 1965 |
| 8 | Kapaia Reservoir | Kauai | 1,114 | 53 | Irrigation | 1910 |
| 9 | Ku Tree Reservoir | Honolulu | 970 | 90 | Other | 1925 |
| 10 | Papuaa Reservoir | Kauai | 921 | 48 | Irrigation | 1914 |
| 11 | Puu Lua Reservoir | Kauai | 888 | 110 | Fish and Wildlife Pond | 1925 |
| 12 | Wailua Reservoir | Kauai | 842 | 34 | Irrigation | 1920 |
| 13 | Upper Helemano Reservoir | Honolulu | 700 | 51 | Irrigation | 1912 |
| 14 | Aepoeha Reservoir | Kauai | 670 | 42 | Irrigation | 1913 |
| 15 | Twin Reservoirs | Kauai | 520 | 49 | Other | 1920 |
| 16 | Kehalani Offsite Retention Basin | Maui | 490 | 30 | Flood Risk Reduction | 2003 |
| 17 | Kauai Lagoons | Kauai | 470 | 13 | Other | 1987 |
| 18 | Halenanahu Reservoir | Kauai | 460 | 40 | Irrigation | 1920 |
| 19 | Aepo Reservoir | Kauai | 457 | 74 | Irrigation | 1901 |
| 20 | Ipuolono Reservoir | Kauai | 450 | 50 | Irrigation | 1910 |
| 21 | Puu Pulehu Reservoir | Hawaii | 445 | 21 | Irrigation | 1910 |
| 22 | Kaneha Reservoir | Kauai | 420 | 51 | Irrigation | 1910 |
| 23 | Elua Reservoir | Kauai | 360 | 34 | Irrigation | 1902 |
| 24 | Mauka Reservoir | Kauai | 345 | 19 | Irrigation | 1910 |
| 25 | Opaeula 01 Reservoir | Honolulu | 320 | 71 | Irrigation | 1910 |
| 26 | Kahakapao Reservoirs | Maui | 309 | 54 | Water Supply | 1990 |
| 27 | Puu Opae Reservoir | Kauai | 295 | 41 | Irrigation | 1930 |
| 28 | Maui Reservoir 73 | Maui | 290 | 25 | Irrigation | 1908 |
| 29 | Maui Reservoir 52 | Maui | 287 | 15 | Irrigation | 1917 |
| 30 | Honokowai - Structure #8 | Maui | 281 | 50 | Flood Risk Reduction | 1995 |
| 31 | Haiku Reservoir | Maui | 266 | 43 | Irrigation | 1904 |
| 32 | Piwai Reservoir | Kauai | 261 | 56 | Irrigation | 1916 |
| 33 | Maui Reservoir 60 | Maui | 260 | 25 | Irrigation | 1917 |
| 34 | Maui Reservoir 74 | Maui | 248 | 28 | Irrigation | 1916 |
| 35 | Kalihiwai Reservoir | Kauai | 242 | 25 | Irrigation | 1920 |
| 36 | Kaupale Reservoir | Kauai | 240 | 50 | Irrigation | 1910 |
| 37 | Kahana Nui Dam | Maui | 225 | 58 | Flood Risk Reduction | 1984 |
| 38 | Waiakalua Reservoir | Kauai | 220 | 23 | Recreation | 1920 |
| 39 | Aahoaka Reservoir | Kauai | 210 | 38 | Irrigation | 1910 |
| 40 | Maui Reservoir 90 | Maui | 201 | 22 | Irrigation | 1917 |
| 41 | Huinawai Reservoir | Kauai | 196 | 47 | Irrigation | 1902 |
| 42 | Omao Reservoir | Kauai | 194 | 32 | Irrigation | 1915 |
| 43 | Lower Kapahi Reservoir | Kauai | 194 | 24 | Other | 1861 |
| 44 | Waikoloa Reservoir No. 1 | Hawaii | 190 | 44 | Water Supply | 1970 |
| 45 | Waikoloa Reservoir No. 3 | Hawaii | 190 | 54 | Water Supply | 1985 |
| 46 | Waikoloa Reservoir No. 2 | Hawaii | 190 | 35 | Water Supply | 1975 |
| 47 | Waimea 60 Mg Reservoir | Hawaii | 189 | 52 | Irrigation | 1957 |
| 48 | Waimanalo 60 Mg Reservoir | Honolulu | 182 | 65 | Irrigation | 1993 |
| 49 | Kumano Reservoir | Kauai | 175 | 48 | Irrigation | 1902 |
| 50 | Maui Reservoir 61 | Maui | 175 | 21 | Irrigation | 1917 |