Demand projections indicate that Oahu's natural ground water supply will be fully developed by the year 2000. Supplementary water resources will need to be developed in keeping with the growth of the economy and population. The author, chairman of the Honolulu Board of Water Supply, authoritatively discusses types of ground water in Hawaii, and areas of interest in water development throughout the Islands. This is followed by an in-depth historical accounting of Oahu's water supply system. The present water resources, population, land use situation, and projects for the future are examined. The Board of Water Supply, which has amply provided Oahu with high quality water, has carried out its responsibilities inefficiently. Management, in terms of utilizing computer technology, is indicated to deal with increasing problems. The issue of whether to combine water supply operations with sewerage functions is presented. Institutional responses to water supply needs, desalination, water recycling and treatment, and energy are other topics thoroughly treated. Although technological innovations can be used to increase supply, specific development projects, conservation measures, and institutional reform are recommended to meet Oahu's water supply needs beyond the year 2020. An extensive bibliography of published and unpublished materials is included. (BP)