Like Oahu’s trash problem, the city’s conundrum over where to locate a new landfill just keeps growing — and the weight of environmental, legal and political considerations is becoming harder to bear.

The latest blow to the city came from Honolulu Board of Water Supply (BWS) chief Ernie Lau, who rejected all six options the city had been considering. The six sites — in pockets of Central Oahu and near the North Shore region — are located over the island’s aquifer system, in the BWS’ No Pass Zone, giving the agency oversight regarding any sewage system.

The city says there are ways to protect the aquifer using protective liners and a collection system for the safe removal of leachate, liquid that would pass through and down from the landfill. But the ongoing Red Hill crisis that erupted a year ago, with fuel from the Navy’s massive storage facility contaminating the area’s water, looms very large.

“Never has the importance of this groundwater aquifer been more apparent, and never has our responsibility to protect it been more paramount,” Lau wrote in a recent letter to Mayor Rick Blangiardi, denying the city’s request to locate any new landfill in the No Pass Zone.

Difficult as that is to hear, the hard lessons of Red Hill and damage to Oahu’s precious water supply must be heeded. Being proactive is the right course to protect drinking water resources for future generations.

So while the city could appeal Lau’s decision to the BWS board, it should not — and instead, must regroup to pursue other options.

That won’t be easy, with tough decisions to get even tougher. The city is facing a year-end deadline to name a landfill site, as ordered by the state Land Use Commission (LUC). The 2019 order requires that the new dump replace the city’s sole landfill at Waimanalo Gulch, which then must close by March 2, 2028, due to environmental justice issues. That landfill in Kapolei above Ko Olina sits on agriculture-zoned land, which requires a special use permit from the LUC.

The city seems to have little choice but to seek an extension from the LUC on picking a new site. In addition to the BWS’ aquifer concerns, site selection is further stymied by a 2020 state law called Act 73, which prohibits any waste or disposal facility in state conservation districts and requires a half-mile buffer between any disposal activity and the nearest residence, school or hospital property line.

All that makes finding a new site more difficult than ever; an interactive map of Landfill Siting Restricted Areas (see 808ne.ws/landfillmap) shows just how few viable options there are after layering in the slew of restrictions.

The urgency for a new landfill could be slowed somewhat by more recycling by Oahu’s residents and tourists, which should be pushed. But even at that, more landfill capacity is the bottom-line necessity. HPOWER can do a lot, but only so much — it can’t burn metals or hazardous waste, for example — and the facility’s incinerated ash ends up in the landfill.

Clearly, the city will need to refresh its search for landfill options that fall outside the BWS’ No Pass Zone, which mostly will mean in Oahu’s exterior areas; plus, it may be forced to consider federal lands that lie closer to shoreline areas, which previously had been deemed nonstarters due to needed approvals from Washington, D.C.

And then there is the elephant-in-the-room option: keeping, then extending, the landfill at Waimanalo Gulch. That would mean legally overcoming the LUC order for the landfill’s shutdown in 2028 — and the city going back on its long-held promise to close the landfill in light of West Oahu residents’ growing opposition to being the dumping ground, quite literally, for Oahu’s trash. There’s also talk of the city applying for a district boundary change to reclassify the current landfill site to urban use.

Just as times have changed, so too have aquifer worries and environmental conditions, especially in the past two years. Those concerns will severely test the political will of the mayor to make a tough decision, one that’s practical but would draw protests from many in Leeward Oahu.