The Honolulu Board of Water Supply says isn’t sure if it will ever be able to reopen three of its drinking water wells that it shut down last month to avoid the chance that jet fuel spilled by the Navy might contaminate its drinking water system.

As a result, areas of southern Oahu, stretching from Halawa to Hawaii Kai, could face water shortages, requiring local officials to ask customers to conserve water, particularly in the summer months, Ernie Lau, manager and chief engineer of the Honolulu Board of Water Supply, told the Star-Advertiser’s Spotlight Hawaii today.

“The situation at Red Hill has put us in a very dire situation right now,” said Lau. “There may be times when you may have problems with low pressure or not have water for a period of time.”

The Navy’s drinking water system that serves about 93,000 people in and around Joint Base Pearl Harbor-Hickam was contaminated with jet fuel in November. The Navy says the fuel likely migrated into its Red Hill drinking water shaft following a Nov. 20 pipe rupture at its Red Hill Bulk Fuel Storage Facility. Thousands of military families have been displaced from their homes for weeks as the Navy works to clean and test its distribution lines.

The water contamination has been confined to the Navy’s drinking water system, which is separate from the Board of Water Supply’s system that serves the majority of Oahu residents. But the Navy and Honolulu Board of Water Supply draw water from the same aquifer. The Honolulu Board of Water Supply quickly shut down its Halawa shaft, which comprises about 20% of the water supply from Halawa to Hawaii Kai, as a precaution, following the Navy’s water contamination emergency. It has also shut down two other drinking water wells.

Tests of the Honolulu Board of Water Supply wells have come up clean and Lau stressed that its water remains safe.

But its the long-term consequences of the fuel contamination that Lau worries about.

Environmental regulators don’t know where the fuel from this most recent spill at Red Hill is located within the aquifer. It’s obviously polluted the Navy’s Red Hill drinking water shaft, but it’s not clear if there is a plume that could be migrating toward the Board of Water Supply wells. The Board of Water Supply fears that restarting its Halawa shaft could hasten the migration of the fuel into its own wells.

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It’s also unclear where fuel from past leaks of the Navy’s underground tanks and piping system has gone, including 27,000 gallons of fuel that was released from a tank in 2014. Board of Water Supply officials say that there aren’t enough monitoring wells to gauge where contamination may be in the aquifer and what direction it is moving.

As part of a corrective action plan handed down the U.S. Environmental Protection Agency and Hawaii Department of Health after the 2014 fuel spill, the Navy was required to complete a modeling study to determine the directions in which groundwater flows in the vicinity of the tanks. The Navy says that the study isn’t technically due yet, while state health officials say there is nothing stopping the Navy from doing the study anyway.

Amid the lack of information, the Honolulu Board of Water Supply says it is looking at sites to develop new wells. Lau said that he doesn’t have an estimate on how much it would cost to replace the capacity it has lost with the three wells being offline.

But the Board of Water Supply has made clear that it could be a long and expensive process.

Erwin Kawata, chief of the Honolulu Board of Water Supply water quality division, told the Star-Advertiser last month that it would take several years to design, construct and fund a replacement equal to the Halawa shaft and cost hundreds of millions of dollars.

The Navy has been focused on cleaning up its drinking water distribution system so its users can resume drinking and using the water. It is also trying to clean up its Red Hill shaft, a water tunnel located at the top of the aquifer where water is pumped into the Navy’s water system. Tests and and visual inspection of the shaft has showed that the well, which has also been taken off-line, was grossly polluted with jet fuel. The Navy hired divers last month to scoop as much of the petroleum from the surface of the water as possible, and is looking at long-term treatment options.

“We will see in the next few months if the Navy will be successful in cleaning up its Red Hill shaft,” said Lau, noting that the level of contamination is extremely high.

In the meantime, Lau said that the Navy should also be focusing on the nature and extent of the underground contamination of the aquifer, how the plumes might be moving and in what direction.

“There is a whole bunch of investigative effort that needs to be undertaken by the Navy,” said Lau.

The Star-Advertiser reached out to the Navy for a response and was told that officials are working to provide information.