Technical Memorandum Report No. 36
Patterns and Trends of Demand for Water in Oahu
Ho-Sung Oh and Hiroshi Yamauchi
September 1972
INTRODUCTION
Since statehood in 1959, the City and County of Honolulu has experienced unprecedented social and economic growth. The total population of Oahu increased from 500,000 to 630,000 during 1960-1970. The tourist industry has grown from 243,000 visitors in 1959 to 1,798,S91 in 1970. Completed construction jumped from 206.1 million dollars to 721.6 million dollars and personal income increased from 1,083.5 million dollars to 2,890.6 million dollars during the same period. Concurrent with these rapid changes, the fresh water consumption has increased from 19 billion gallons in 1959 to 35 billion gallons in 1970. In terms of an annual average daily water consumption, the increase has been from 53 million gallons per day to 100 million gallons per day. This is approximately an 88 percent increase in water consumption through the municipal water supply system. The Honolulu Board of Water Supply, over the last twelve years, has exhibited a much faster growth rate in water deliveries than the population increases. Water supplies by private agencies are mostly developed for the sugar and pineapple industries and the military. The growth of these uses has been rather constant over time. But if they are included, the total water consumption is approximately 4.3 times higher than that of municipal water consumption alone or 430 million gallons of water per day for the island of Oahu. Although more than 90 percent of the 430 million gallons is supplied by ground-water sources, the total ground-water discharge is presently still within the 525 million gallons per day maximum limit of developable ground water for Oahu. Based on past rates of increase in consumption, however, the limit would be reached before the end of the century. Furthermore, reviewing the past experience of regional imbalances of supply and demand and extreme seasonal peak demands, the water situation in certain areas might reach critical limits sooner than might be expected. In view of these facts, the meaning of the changes and direction of changes of water demands should be thoroughly reviewed to provide a sounder basis for the planning of future development and for the conservation of the island’s water resources. The objectives of this study on water demand were: 1. To reconstruct and evaluate the patterns and trends of water demand in Oahu. 2. To identify and describe factors affecting demand for water in various Board of Water Supply planning areas and for different uses. 3. To clearly delineate the role of these factors and their interrelationships. 4. To isolate and analyze any major problems including the institutional factors which might have a bearing on the patterns and trends of future demand. 5. To make recommendations toward improvement in water planning and conservation.