As the Navy’s Red Hill fuel tank catastrophe has shown, environmental dangers are embedded in the aina — largely unbeknownst to the general public, until disaster occurs.

Now comes news that even the state Department of Health (DOH), the regulator of underground storage tanks, has been out of the loop to what lurks beneath — and that’s unsettling.

On June 2, DOH fined the state Public Safety Department (PSD) $104,125 for underground fuel storage tank violations at its Halawa Correctional Facility — about a year after DOH first learned of the 30-year-old tank’s existence. The tank had been installed in June 1993, DOH said, but without proper notification and permitting.

The unregistered, 1,000-gallon underground fuel tank system stores diesel fuel for an emergency generator. After launching an investigation into the facility on June 24, 2022, DOH inspectors this month cited PSD for numerous violations, including: failure to notify DOH of the system within 30 days after installation; failure to conduct annual tightness testing on spill prevention equipment; and failure to conduct maintenance walk-through inspections on equipment every 31 days.

To be sure, the amount of fuel stored beneath the Halawa prison seems minuscule compared with the 104 million gallons sitting in the Navy’s 20-tank fuel facility at Red Hill.

But if the Red Hill spills in 2021 proved anything, it was that Oahu’s precious water supply can very quickly be compromised by fuel facilities operating without proper safeguards and oversight. When some 20,000 gallons of jet fuel contaminated Red Hill water wells, it affected 93,000 Hickam-area water users and sickened hundreds. Serious harm was done to health and environment from inadequate and deferred maintenance.

As for the prison’s underground fuel tank: The Public Safety Department on Tuesday submitted a request to DOH for a hearing on the concerns raised in the notice of violation.

PSD said that it’s been working diligently to immediately address and resolve the matter, after making a good-faith effort in June 2022 to notify DOH of the underground tank, which led to the inspection. That, at least, is positive — as was PSD’s statement that testing conducted so far indicates no evidence of leaks.

Still, it needs to be determined just how the prison’s fuel tank was installed without the proper permitting and oversight. Further, it now behooves DOH — and all other state agencies — to investigate whether other similar projects might have been built surreptitiously over the years, posing a risk to water and aina.