OAHU ISLAND

Oahu is the third largest Hawaiian Island, measuring 71 by 48 km at its extreme dimensions and having an area of about 1,564 km2. It emerged from the ocean during the Tertiary and possibly early Pleistocene. Two mountain ranges dominate the island's topography; The Waianae Mountains rises to 1,227 m while the Koolau Mountains reach 960 m.

According to Timbol and Maciolek (1978), 54 perennial streams are recognized on Oahu. Fifty-three percent of these are continuous, 47 % are interrupted, and 57 % (31 streams) are channelized. A total of 134 km of modified stream channel occurs among the 31 altered streams on Oahu. The estimated relative percentage of channelized reach on Oahu is:

Lined channel - 43%

Cleared and realigned - 27%

Revetment - 23%

Blocked - 6%

Elevated culvert - <1%

Extended culvert - <1%

Among channelized streams, Waikele Stream on Oahu's leeward side is the largest on the basis of stream length and watershed area. Keaahala Stream on the windward side is Oahu's smallest stream. The altered sections of the channelized streams on Oahu averaged 16 % (range 2 - 100%) of total stream length. Fifty-seven percent of Oahu's streams have altered channels, 58 % have water exported, and all have roads crossing over them. There were, therefore, no physically pristine streams identified (in the report) on Oahu.