A top Navy official now says that as much as 19,000 gallons of fuel may have been released from a Red Hill fuel tank May 6, eventually migrating last month into the Navy’s drinking water system and the faucets of thousands of military families.

The source of the water contamination crisis that has affected approximately 93,000 people in the neighborhoods in and around Joint Base Pearl Harbor-­Hickam continues to be investigated. But Capt. James “Gordie” Meyer, commanding officer of Naval Facilities Hawaii, said Monday that he and others have a “working theory” that the fuel spilled into a lower tunnel and ended up being pumped into a pipeline that’s part of the facilities’ fire suppression system.

That pipeline then ruptured months later, on Nov. 20, spewing thousands of gallons of fuel and water, a portion of which Navy officials now think flowed into a drain used to release rainfall infiltration into the environment.

Meyer’s remarks were made during a 13-hour contested case hearing Monday that stretched into Tuesday morning. The Navy is contesting an emergency order issued earlier this month by the state Department of Health that it drain its Red Hill fuel tanks, clean up the contamination and address safety issues at the facility before seeking state permission to resume operations.

A hearings officer overseeing the contested case is expected to issue a recommended order early next week, and DOH Deputy Director Marian Tsuji is then expected to make a final determination.

Attorneys for DOH, as well as the Honolulu Board of Water Supply and Hawaii Sierra Club, who are parties to the case, seized on the May 6 incident, as well as the Navy’s confusion about whether that was indeed the source of contamination of its water system, as further proof the Red Hill facility poses an imminent danger to Oahu’s water supply.

The fuel farm contains 20 massive underground fuel tanks that sit just 100 feet above an aquifer that serves as a major source of drinking water for southern Oahu.

The Navy has long argued that it has adequate leak detection and prevention systems in place, but the current water contamination crisis has highlighted their weaknesses.

“How did we find out there was fuel in the drinking water?” said Ella Foley Gannon, an attorney with Morgan Lewis in California, who is representing the Board of Water Supply in the contested case hearing. “Because people turned on their taps and smelled it, and they tasted it, and they saw their dogs getting sick and their children getting rashes on their bodies. That’s how we knew it — not by any early warning systems that the Navy has been operating.”

On May 6 the Navy said in a news release that approximately 1,000 gallons of fuel had been released from a pipeline at its Red Hill Bulk Fuel Storage Facility. “As designed, the fuel release went into a containment system in the tunnel where the pipeline is located, and the fuel was recovered. There appears to be no release into the environment,” Navy officials said at the time.

Then in October, following a months-long investigation into the event, the Navy said the fuel release was actually 1,618 gallons, not 1,000, and that all but 38 gallons was recovered with no indication the spilled fuel had affected the groundwater.

As part of that investigation, the Navy ordered a “root cause analysis” of what went wrong, which was performed by Austin Brockenbrough, an engineering consulting firm. Buried in a table detailing the sequence of events of the May 6 release was a note that read, “Tank 12’s net volume finally drops 473 (barrels) over 50 seconds.”

Gannon asked Meyer during Monday’s hearing what happened to those 473 barrels of fuel, which translates into 19,000 gallons.

“I and others have a working theory, that’s still under investigation, that fuel, at least some of that, was released into a lower tunnel by tanks 18 and 20,” Meyer said. That fuel is believed to have entered a recovery sump and was then pumped into a fire suppression pipeline, he said.

That pipeline ruptured Nov. 20. At the time, Navy officials said that about 14,000 gallons of fuel and water spilled from the drain line. “There are no signs or indication of any releases to the environment, and the drinking water remains safe to drink,” according to a Navy news release on Nov. 21.

Navy officials now say that’s apparently not the case and that fuel did migrate out of its Red Hill facility and into its drinking water well. Water users began reporting fuel odors coming from their water on Nov. 28.

David Henkin, an attorney for Earthjustice who is representing the Hawaii Sierra Club in the contested case, said “it provides cold comfort to the public” that the Navy isn’t sure where the 14,000 gallons that spilled beginning Nov. 20 came from. “They suspect it came from the May 6 release,” he said.

“If they don’t know where the fuel is coming from and where it is going, and we heard from Capt. Meyer that maybe there was a release on May 6 of not 1,600 gallons, but maybe it was closer to 19,000 gallons, that is the existential threat we face,” Henkin said.