Ka Wai Ola - Office of Hawaiian Affairs, Volume 9, Number 9, 1 September 1992 — Oʻahu Water Plan stresses conservation [ARTICLE]

Oʻahu Water Plan stresses conservation

by Pearl Leialoha Page Increasing public awareness of the neeel to conserve water is a major factor in planning for future water use on O'ahu, according to the O'ahu water plan. While the plan predicts that there will be enough water to provide for projected growth through 2010, the margin for reserves is slim. The plan was presented during an information meeting in Honolulu July 31, the last of a series of such meetings held throuehout the state.

Some of the major projects planned in the next 20 years include: Kapolei Village, requiring 2.9 million gallons a day (mgd); Honolulu International Airport Expansion whieh will need an additional 900,000 mgd bringing its total to 2.7 mgd; and Keehi Lagoon Development, 1.1 mgd. Agricultural projects needing a mixed use of potable and nonpotable water include Kahuku Agricultural Park, 2.0 mgd; and Waipahu Livestock Agricultural Park, 3.0 mgd.

Between now and 2010, Ewa is expected to grow by 194 percent, followed by East Honolulu at 21.6 percent, and Central O'ahu 20 percent. The windward side is expected to decrease in population, reported Rodney Funakoshi of Wilson Okamoto & Associates hired as a consultant by the city and county. The challenges eome when many of the future projects occur in areas where the aquifer is already fully allocated, then water has to be brought in from other areas. From preliminary

studies the north sector. encompassing Waialua, Mokuleia and Kawailoa, shows promise as a developable water source, according to the plan. It is also estimated that a third of the potable water now used by sugar will be transferred to residential use as sugar continues to decline. The other two-thirds would be taken up by new diversified agriculture. Updated stream flow and hydrologieal studies for O'ahu identify the windward aquifers of Ko'olaupoko, Kahana and Waimanalo as areas

where new wells should not be eonsidered. Withdrawing additional ground water would deplete either stream flow or wetlands and therefore should not be considered as developable water sources. Idealistically this should not affect current water users, however there are a number of new projects coming up that will use additional water from this area, said Dave Martin, Native Hawaiian Advisory Council, a water rights watchdog group. "The main problem is no one has defined how mueh water ean be taken out without being detrimental," he said.

Currently, the residents, businesses, military and sugar use 294 million gallons of potable water a day. Revisions to the plan have changed the amount of the sustainable water yield from 472 mgd to 465 mgd. This is actually a correction to the previous count whieh included some figures more than onee and not a result of growth, explained Eric Hirano of the Department of Land and Natural Resou rces. Of the 465 mgd only 416 mgd are developable, Funakoshi pointed out. In 2010 it's projected that nearly a million residents will need 365 mgd of potable water, or 88 percent of the sustainable yield. That's not mueh of a margin for water reserves, Funakoshi said.

The state water plan calls for an aggressive water conservation and education program with a view to decreasing the per capita use of water. What about 0'ahu's muhimillion visitor populaUon? Herb Mirakami of the Board of Water Supply explained that water used by visitors is accounted and projected for in the BWS per capita figures.

The city and county of Honolulu has already set a priority for water use, designating affordable housing and recreational use, such as parks, top priority. Other ordinance strategies for water management on O'ahu include: refining the process of counting sustainable yields to give more

accurate information and plan water developments; continuing to inventory surface water use; transfering sugar allocations to munieipal use, encouraging conservation programs, such as the use of low-flow fixtures; developing and using non-potable water sources for landscaping; and pursuing demineralization and desalination.

A demonstration desalination plant in 'Ewa is now producing about .5 mgd cf potable water from brackish ground water sources, the plan states, and a BWS study is identifying other potential brackish sources whieh could support similar desalination plants. The BWS' new rule requires nonpotable sources for landscaping and cemeteries and will even provide transmission lines to the site in order

to exchange non-potable for potable, Funakoshi said. It also has two pilot programs in plaee in city residential buildings to monitor the effectiveness ~ of dual-flush toilet systems. Further, the Honolulu City Council recently passed two water conservation ordinances requiring all new

buildings to be equipped with ultralow flush toilets and low-flow fixtures. All nonresidential buildings are also required to retrofit with ultra-low flush toilets and low-flow fixtures by 1992. Time extensions may be granted and other conservation measures substituted should plumbing systems prevent a retrofit. The county water plan goes through a revisions process every two years to reflect changes and new challenges.