This month, the state Commission on Water Resource Management is expected to decide whether or not to accept or reject a petition from the Honolulu Board of Water Supply to designate the Waiʻanae aquifer sector as a groundwater management area.
Waiʻanae is the only region on Oʻahu that is not a designated water management area, where the Water Commission decides who gets water and how much.
A decade ago, the BWS sent a letter to the Water Commission asking the agency to initiate the designation process for the Waiʻanae area, which has long lacked the developed water resources to meet its needs. When that did not happen, the BWS last year drafted a petition to designate, which it formally submitted in January.
According to the petition, the BWS believes at least three of the commission’s criteria for groundwater management area designation have been met: Criterion 1, existing and future withdrawals meet or exceed 90 percent of the sustainable yield; Criterion 3, ground water levels are declining; and Criterion 7, serious disputes are occurring.
The Waiʻanae aquifer sector includes five aquifers: from south to north, they are Nānākuli, Lualualei, Makaha, Waiʻanae, and Keaʻau.
Nānākuli’s sustainable yield is 1 million gallons a day; the other four aquifers each have a sustainable yield of 3 mgd, for a total of 13 mgd for the entire sector.
For years, more than half of the water consumed in the Waiʻanae sector has been imported by the BWS from wells in Kunia and Waipahu that tap into the Pearl Harbor aquifer. The rest comes from sources within the sector.
Although the Waiʻanae sector has a sustainable yield of 13 mgd, tapping all of that is impracticable, the BWS argues.
“While undeveloped portions of [sustainable yield] exist in the Wai‘anae aquifer sector, it is not practicable to develop it. The 2009 BWS Wai‘anae Watershed Management Plan noted a ‘significant portion of the remaining untapped supplies exist in remote areas of the island where growth is limited, infrastructure does not exist or pumping may affect stream flows and will be subject to future measurable [interim instream flow standards].’ Development of further water sources in Nānākuli, Lualualei, and Kea‘au is not practicable due to the economic cost of developing these sources as well as hydrogeological factors,” the petition states.
What’s more, nearly 97 percent of the Waiʻanae aquifer’s sustainable yield is being pumped and water levels in the Makaha aquifer are declining.
“Pumping in Mākaha in 2016 was nearly at the Criterion 1 threshold. Historically, it has been possible to pump Mākaha to nearly the current SY of 3 mgd. However, due to declining water levels, BWS has reduced pumpage,” the petition states.
“If Makaha SY is reduced due to declining rainfall and recharge, pumping would certainly exceed 90% of SY,” it adds.
According to groundwater recharge estimates released by the U.S. Geological Survey last year, the Makaha and Lualualei aquifers are two of the three on the Oʻahu that are predicted to see declines in recharge under the most favorable climate change models that predict a slightly wetter future for most areas across the Hawaiian islands.
Using other models that project reduced recharge in all aquifers on the island, the USGS determined that Nānākuli and Lualualei aquifers would suffer the most, with declines of more than 60 by mid-century and more than 80 percent by 2100.
Under the water-restricted paradigm, the Department of Hawaiian Home Lands has development plans that will require 4.863 mgd. The BWS also identified 0.863 mgd of other authorized planned use within the sector,
Not accounting for any declines in aquifer recharge due to climate change, recent pumping and authorized planned uses total nearly 11 mgd, or 84 percent of the sector’s sustainable yield.
“Wai‘anae, Mākaha, and Nānākuli aquifer systems should be deemed to meet Criterion 1 based on historical and ongoing pumping and [authorized planned use], while other systems do not. Historical and ongoing pumping and [authorized planned use] across the sector are approaching 90 percent of SY before analyzing whether SY can be properly applied in Waiʻanae. Developable yield in other parts of the Wai‘anae sector is likely far below sustainable yield, and current development already represents a significant portion of developable yield in those areas. …
“The observed, existing decline in Mākaha water levels may indicate further water level declines across Wai‘anae. Both statistical and dynamical climate change predictions caution against relying on a wetter climate future. This means less rainfall in Wai‘anae, less recharge of Wai‘anae aquifers, and therefore a likelihood for a reduced sustainable yield. CWRM could appropriately find decline in Mākaha ground water levels requires Wai‘anae sector designation,” the petition states.
With regard to whether serious disputes are occurring in the area regarding groundwater, the BWS first points to the spillover effects of the repeated leaks from the U.S. Navy’s Red Hill underground fuel tank system, which sits above the Pearl Harbor aquifer.
“BWS shut down three pumping stations (Halawa Shaft, Aiea Wells and Halawa Wells) as a preventative measure against pulling fuel contaminants into the BWS water system from the contaminated aquifer. … BWS is compensating for the shutdown by transferring more water from sources tapping the Waipahu-Waiawa aquifer to Honolulu systems and accelerated its water conservation messaging, Water Sensible rebate, and leak detection programs. The transfers of water from the Waipio water system reduces the available water supply for the Waipahu, ‘Ewa, and Wai‘anae water systems, although not to the extent where mandatory conservation and building restrictions are necessary.
“Though the Pearl Harbor aquifer does not underlie Wai‘anae moku, it is connected to water sources used to supply areas from Nānākuli to lower Wai’anae. … Serious disputes over contamination of sources in Pearl Harbor could affect the availability of water resources for Wai‘anae, particularly as climate change modeling predicts a drier overall future for leeward O’ahu,” the petition states.
In addition, the BWS notes that over the years, community members and organizations — including the Waiʻanae Neighborhood Board and the Association of Hawaiian Civic Clubs — have called for the restoration of flow to streams and other natural waterways that have suffered, in part, due to the development of water sources.
One of those developments includes the Navy’s drilling for water in Lualualei. The BWS cites a “well-known controversy” over the depletion of a culturally important spring, Pūhāwai. A tunnel drilled about a century ago cuts through several springs, leaving Pūhāwai dry.
“Since the 1930s when the Navy drilled its water sources in Lualualei, many of the military operations at Lualualei have downsized to a staff of thirty-five, and families have long moved away. Lualualei tunnel continues to remove water resources. Currently, the Navy obtains approximately 380,000 gpd from Lualualei sources. That amount would provide enough water for 950 single family homes at a relatively high duty of 400 gal/day-unit. A recent aerial inspection of the Naval magazine disclosed about 20 single family homes, a few large buildings with irrigated areas and approximately 18 miles of water pipeline.
“Many in the community, including area elected representatives and other officials, assert water is being wasted or dumped by the U.S. Navy on Lualualei lands. State Senator Shimabukuro observed ʻlarge pipes close to the Navy land, where freshwater was gushing out ʻand was ʻconcerned about them wasting water. Also, since there are historic lo‘i on the Navy lands, restoring these would require some of this water.ʻ Similar to Senator Shimabukuro, longtime Wai‘anae resident William Aila also referred to ʻNavy water pipes, which are supposedly leaking/ ‘dumping excess waterʻ and expressed that he ʻwanted to know where the Navy is dumping all the water,ʻ” the petition states.
Criterion 6 for groundwater designation is whether excessive preventable waste is occurring. The BWS stated in its petition that while it lacks evidence that water is being wasted, “this may be due to a lack of information on preventable wasting from private or military water systems in Wai’anae and Lualualei that could indicate Criterion 6 is met.”
Last month, the Water Commission voted to extend the 60-day deadline for the chair to make a recommendation on the BWS petition. The extension was to allow more time for the mayor, City Council, and BWS to comment on the petition.
If the chair recommends accepting the petition and the Water Commission agrees, a public hearing will be held. The Water Commission will also gather the scientific and other information necessary to determine whether or not to designate. After further consultation with the mayor, City Council, and the BWS, the commission chair will make a recommendation on whether or not to designate. The commission would then have 90 days to act on that recommendation.
At the commission’s February meeting, commissioner Lawrence Miike said, “In my opinion, the whole state should have been designated.”
Commissioner Aurora Kagawa-Viviani said she appreciated the BWSʻ petition, because it may help the commission manage resources “in the most water-limited region on our island.”
Commission deputy director Ciara Kahahane added that despite the time extension to allow for more comment from the city, “To be frank, I think there is ample information in the petition on which to proceed.”
— Teresa Dawson
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