The Honolulu Board of Water supply says it has detected petroleum-related chemicals in a monitoring well in Moanalua Valley, elevating concerns that fuel contamination from the Navy’s Red Hill fuel facility is traveling through the aquifer and putting a major source of drinking water for southern Oahu at risk. The findings also raise concerns that contaminants could be migrating in an unanticipated direction, increasing the urgency of doing more groundwater flow studies.

The BWS said Thursday that it detected total petroleum hydrocarbons in water samples that were tested at the well, indicating the presence of fuel, as well as polycyclic aromatic hydrocarbons, or PAHs, are a class of chemicals that can occur naturally in crude oil and gasoline and are also produced when it’s burned, according to the U.S. Centers for Disease Control and Prevention. A number of the chemicals that were detected are known carcinogens.

“The recent contaminant detections in our DH-43 monitoring well are warnings that we cannot ignore,” said BWS Manager and Chief Engineer Ernest Lau in a news release. “Our precious and irreplaceable water resources are at risk of further contamination every day the fuel remains in the Red Hill tanks. We urge the Navy to expeditiously defuel and permanently close the Red Hill facility — Ola i ka Wai.”

The well is one of two that the BWS has been testing to check for the possible presence and migration of contaminants in the groundwater around Red Hill and does not mean that Oahu’s drinking water system is contaminated. BWS officials emphasized Thursday that the water remains safe to drink.

The BWS said that it had met with the state Department of Health and U.S. Environmental Protection Agency and that there is agreement that the low levels detected are not expected to pose a health hazard. “However, while not a current health emergency, it needs attention and continued monitoring,” BWS said.

DOH said more investigation is needed to determine whether the contamination is from Red Hill. But BWS officials said during an interview that they thought the data, particularly when compared with similar detections in the Navy’s monitoring wells, provides sufficient evidence that it is.

DOH has been monitoring a plume under the Red Hill facility in an attempt to gauge the movement of fuel from 2021’s leaks. Earlier this year DOH said that data had indicated that the contaminants had migrated westward in the direction of BWS’ Halawa shaft, which had supplied about 20% of the water for urban Honolulu until BWS shut it down as a precaution in late 2021.

Overall, DOH data indicated that the fuel contamination levels were decreasing.

But Honolulu water officials have remained on edge, worried that fuel contamination from the Red Hill facility might find its way into its drinking water system, which is separate from the Navy’s, creating a more daunting crisis that could affect hundreds of thousands of Oahu residents.

In addition to the Halawa shaft, the BWS shut down its Aiea and Halawa wells as a protective measure, straining water resources. The BWS has been urging Oahu residents and businesses to conserve water since April.

The monitoring well where the petroleum contamination was detected is about 1,500 feet to the southeast of the Red Hill facility, which is equivalent to the length of about four football fields. The detections of TPH and PAH are particularly alarming because it suggests that fuel contamination from Red Hill is migrating in an unexpected direction, from west to east.

Erwin Kawata, who oversees water quality for BWS, said that the detections in the monitoring well came as a surprise. He had tested the well following a 2014 spill at the Red Hill facility and found no indications of petroleum contamination. Given the impact of the 2021 fuel releases at Red Hill, he decided to check the well again.

“We didn’t expect to see anything there,” he said. “I checked in 2015, and I didn’t see anything in 2015. So there was no reason to think it was there. But I just happened to go and do it, particularly because of the major amount of contamination that affected Joint Base Pearl Harbor.”

Kawata said that the detections don’t provide conclusive evidence that contamination flows eastward from the tanks and that more monitoring needs to be done to see whether contaminant levels are increasing or decreasing. But he said it adds to the urgency of completing groundwater flow studies not just to the west of Red Hill, but now also to the east.

Environmental regulators had required the Navy to do a groundwater study following the 2014 fuel release at Red Hill, but it was never finished.

UH water sampling controversy

In other Red Hill developments, the University of Hawaii said that it will hold a news conference today to answer questions about water sampling data that it posted briefly Tuesday on its website before quickly taking it down, but not before numerous people took screen shots. A news conference planned for Tuesday to discuss the water testing was also scrapped.

The test results seemed to show that a UH Red Hill task force had found fuel contamination in a small number of drinking water samples taken from the Navy’s water system as late as May — two months after the DOH and Navy said that the water was safe to drink.

On Thursday a law firm representing families affected by the 2021 fuel spills at Red Hill called on the Navy to evacuate families in response to the findings.

“Data released by the University of Hawaii Red Hill Task Force this week confirms what our clients already knew to be true: their water is still contaminated,” attorneys for Just Well Law wrote in a letter to Navy Vice Adm. Darse E. Crandall. The law firm says it represents close to 150 affected families.

DOH, which oversaw extensive water sampling following 2021’s Red Hill water contamination crisis, says the fluorescence testing method employed by UH is not reliable and is subject to interference and false positives. The methodology is not certified by the EPA.

UH spokesman Dan Mei­senzahl said Thursday that the method used by UH detects something that could be fuel, but it doesn’t identify the chemical. He said the UH data does not contradict DOH’s conclusions that the water is safe to drink.