Designed during World War II as a bombproof reserve, Red Hill Underground Fuel Storage Facility houses 20 aging tanks — each large enough to swallow Aloha Tower. It helps serve an ongoing U.S. military need for “uninterrupted access to large volume, secure and sustainable fuel storage facilities” in Hawaii and throughout the Pacific. But it’s also perched just 100 feet above Oahu’s primary aquifer, which supplies drinking water to more than 600,000 residents, from Moanalua to Hawaii Kai.

Concern about its potential to taint drinking water quality shot up in the aftermath of a 27,000-gallon fuel leak in January 2014. The next year, the Navy (Red Hill’s operator) entered into an agreement with the U.S. Environmental Protection Agency and the state Health Department (site regulator) that requires a series of studies and upgrades over a span of 20 years.

The Hawaii Sierra Club rightly contends that pace is too slow, particularly with looming EPA budget cuts under the Trump administration. Given the proposal to cut EPA funding by about 30 percent, we cannot rely heavily on the federal government to protect our environment or public health.

The nonprofit is now applying some needed arm-twisting, to have the Navy speed progress. On Wednesday, it delivered notice to the Department of Health that the agency is in violation of a 1992 state law that required replacement or upgrades of underground systems storing hazardous material by late 1998. The DOH has yet to respond to the petition, which could serve as a prelude to a lawsuit against the state.

For safety’s sake, the Sierra Club and others must continue to force the issue. In addition to complying with the upgrades law, the DOH needs to clearly specify terms for cleanups and decommissioning of all underground tanks in Hawaii, most of which are tiny compared to those under Red Hill. Although the military facility is a hidden feat of engineering — constructed in four years — it was not built to last forever.

It’s frustrating to see that Navy and environmental regulators have yet to even settle on exactly how the tanks would be upgraded. Some state officials and others want what’s now considered the closest thing to a sure-bet seal: a double-walled retrofit. The Navy, which has, in the past, expressed concerns about cost, is weighing new technology and other ideas. At least six options are under review. But three years have passed since the worrisome leak. A selection should be made quickly.

The longer the wait, the more likely it is we’ll see more trouble with the 77-year-old tanks. Studies document leaks dating back to 1947, corrosion of liners, and gauge risk of a catastrophic fuel release, which the Board of Water Supply says could pollute the aquifer and our water supply for many years.

Earlier this year, the Navy assured state lawmakers that the tanks are not leaking. In written testimony, it said: “validated testing confirms, and all parties agree” the drinking water from the shaft is safe. Since the 2014 leak, the Navy has stepped up testing of drinking and groundwater and added monitoring wells. Also, over the past decade, the federal government has made $200 million in improvements, ranging from installation of groundwater and soil vapor monitoring systems to structurally reinforcing and renovating tunnels and passageways.

EPA officials echo a sense of calm in a May status update, which states that drinking water in the area meets federal and state standards, and that recent tests had not detected any fuel leaks.

But catastrophe scenarios — touched off by an earthquake, for example — are unnerving. The BWS estimates that structural failure could sink more than 1 million gallons of fuel into groundwater and potentially several million gallons into Halawa Stream and Pearl Harbor. The semi-autonomous agency that manages Oahu’s municipal water resources wants the Navy to double-line tanks or relocate them away from the aquifer. The Navy and environmental regulators should pick one or the other, and soon.

The very existence of the Red Hill tanks was a state secret until the early 1990s, when the facility was declassified. Now, with its strengths and flaws under glare of public scrutiny, it’s time to finalize a plan of action for the site’s future and promptly get the job done.