Protecting the Wai of Wai‘anae
By Wayne Tanaka, Chapter Director | Reading time: 3 minutes
All of Oʻahu may soon be designated as a groundwater management area, after a May 20 decision by the Commission on Water Resource Management (CWRM) to “accept” the Honolulu Board of Water Supply’s (BWS’) designation petition for Waiʻanae.
Waiʻanae Mountains. Photo: Andrew K. Smith
Groundwater management area designation requires all uses of groundwater to be reviewed and approved by CWRM, which must ensure the sustainability of the resource, balance various needs for water, and ensure that all water uses are consistent with the public trust. Those wishing to use groundwater in a designated area must submit a ground water use permit application, describing how their use of water is “reasonably beneficial” or for a public trust purpose, and justified in light of any impacts to competing public needs. Applications for private, commercial uses of water are subject to a heightened level of scrutiny, and must demonstrate why the private use of a public trust resource should be permitted.
In short, designation would allow CWRM to decide who gets how much water for what purposes, consistent with the public trust and the needs of present and future generations.
The Waiʻanae Aquifer Sector Area is the only place on Oʻahu that is not already designated as a ground water management area.
The BWS petition for the designation of Waiʻanae was submitted in early 2025, after years of research and consultation with CWRM staff and local community groups, including the Waiʻanae and Nānākuli Neighborhood Boards. Reasons the BWS is seeking designation include:
Current pumpage rates from existing wells in Waiʻanae already exceed 90% of the current “sustainable yield” of available water - which is likely to be revised downward in light of reduced rainfall, declining groundwater levels, and climate trends;
Future anticipated water needs, including for the Department of Hawaiian Home Lands, Kaʻala Farms, Puʻuhonua o Waiʻanae, and a Korean church’s “mini homes” proposal, among others, will further increase demand for ever more limited water resources;
Unexploded ordnance and toxic chemicals from formerly used military defense sites - such as at Mākua Military Reservation and Lualualei - may contaminate and further reduce the availability of usable groundwater;
Reports from community members suggest that a significant amount of water waste may also be occurring, particularly from Navy water systems at Lualualei; notably, Navy wells in the valley continue to pump 380,000 gallons per day - enough water to serve 950 single-family homes - yet the Navy’s system only serves 20 single family residences and a handful of large buildings;
Serious disputes regarding water use may be occurring and are likely to occur, in light of the contamination of groundwater at Puʻuloa, which is used to meet some of Waiʻanae’s needs, and repeated community calls to restore streams, springs, and traditional agriculture - long disrupted by groundwater pumping - by the Waiʻanae Neighborhood Board and the Association of Hawaiian Civic Clubs, among others.
Accordingly, oversight by CWRM through designation would help to balance the needs of the environment and the community - including present and future generations - and protect the wai of Waiʻanae from hoarding, waste, and inappropriate uses inconsistent with the public interest.
CWRM’s decision to “accept” the BWS petition for ground water management area designation will now trigger a public hearing to take input on whether or not to approve the petition. Additional scientific studies and fact finding, as well as consultation with the Mayor, City Council, and the BWS board, will also need to be conducted, followed by a final recommendation and CWRM decision on whether or not to approve designation will then take place. If approval is granted, the ground water use permit application process will commence.
The BWS petition and CWRM staff submittal can be read here, and the CWRM discussion and vote on whether or not to accept the petition can be viewed here.