Navy officials told federal lawmakers Tuesday that they will comply with an emergency order issued by the state of Hawaii to defuel the service’s underground Red Hill tanks. However, in this pivot, which follows weeks of vowing to fight the order and a contested hearing, officials did not rule out the possibility of further legal challenges.

The fuel in the Red Hill tanks is the suspected source of the contamination of the Navy’s drinking water system on Oahu, which serves some 93,000 people. Also, the tanks, which can hold up to a total of 180 million gallons of fuel, sit 100 feet above a critical aquifer that provides much of the island’s drinking water.

Rear Adm. Blake Converse told members of the U.S. House Armed Services Committee during a hearing on the water crisis that Pacific Fleet commander Adm. Samuel Paparo issued directives Friday to begin efforts to comply with the order.

“We are in receipt of the emergency order issued by the Hawaii Department of Health, and we are taking action because it is a lawful order to comply with,” Converse said.

However, when asked whether the Navy has any further plans to contest the order, Converse said, “I am not a part of the decision-­making apparatus on whether or not the Navy is going to contest that order. I don’t have any information on that at this point.”

Responding to the Navy’s move, Kaitlin Arita-­Chang, a state Department of Health spokeswoman, said, “Basically, (the Navy) is complying as they have to in order to follow the law.”

The state’s emergency order went into effect Jan. 3 following a contested case hearing in which DOH dismissed the Navy’s arguments that the state didn’t have the legal authority to issue the order. The Navy has until Feb. 2 to contest the decision in court, and the order remains in effect unless a judge issues a stay.

The Navy has already been fulfilling many aspects of the emergency order. For instance, it halted Red Hill fueling operations in late November and has been taking steps to clean up jet fuel from its Red Hill shaft. But the Navy has balked at a requirement that it defuel its Red Hill tanks and make any necessary safety improvements before seeking state permission to resume operations.

Under the emergency order, the deadline for defueling the tanks is not specific. The Navy is required to submit a plan to DOH by Feb. 2 that details any system upgrades or fixes that need to be completed in order to safely drain the massive tanks. Upon DOH’s approval of a work plan, the Navy must then make any improvements. After completing needed repairs, the Navy is required to defuel the tanks within 30 days.

During Tuesday’s hearing, U.S. Rep. Kai Kahele, D- Hawaii, told Navy leaders, “This order has witnessed broad support from the communities of Oahu, the governor, Department of Health, the state commission on water resource management, the City and County Board of Water Supply, City Council members, state legislators.” He added, “The whole of government in Hawaii believes that the Navy should comply with this order.”

While Navy officials had previously argued that the state lacks the legal authority to compel the service to defuel the tanks, state officials maintained that they had both the authority and the responsibility to protect and regulate drinking water.

U.S. Rep. Ed Case, D- Hawaii, told Navy leaders he wanted the military to formally acknowledge the state’s legal authority.

“This is coming off as a voluntary compliance, and a voluntary compliance can at some point in the future be reversed, and that is the fear of the state of Hawaii,” said Case. “And so I would strongly urge the Navy and the Department of Defense, as you analyze your clear legal options in terms of the emergency order, to confirm that the state of Hawaii does in fact have this authority.”

The Navy has argued that proposals to build a new facility elsewhere to store Red Hill’s fuel would be costly and logistically burdensome. But the constant repairs and upgrades needed to operate the World War II-era facility have also proved costly — as has the response to the current crisis.

“I can tell you that the running costs — when you consider temporary lodging (for affected households) and the transportation and the leasing of all the filtering assemblies and all the other things that we’ve had to do to clean up the well and water distribution system — right now the tally is well over $250 million,” Converse told lawmakers.

Kahele toured the facility last week along with state and local legislators. During the hearing he recalled seeing eight granulated activated carbon filtration tanks — or GACs— set up outside the Red Hill well. The Navy’s plan is to draw and filter water from the well and then discharge it into nearby Ha­lawa Stream. If the Navy gets approval from state and federal regulatory agencies, this process could start as soon as Jan. 20.

“I have serious reservations about releasing such a high volume of treated water into the stream due to the possible unintended consequences and downstream effects,” said Kahele, adding that alternative options should be on the table. Kahele said that ultimately, if all state and federal agencies agree to go forward with the plan, he wants the public to be notified before the process begins and for officials to explain to local residents exactly what they are doing.

“There are people that fish in that stream, there are people that crab in that stream, and that is why I think the Navy should make sure the public is well aware before that discharge commences,” Kahele said.

During the hearing, Converse said the Navy contends that “operator error” caused the release of fuel that has contaminated the drinking water. Previously, the Navy said fuel from a May spill apparently descended into a lower tunnel and ended up being pumped into a pipeline that’s part of the facility’s fire suppression system, which ruptured months later, on Nov. 20, spilling thousands of gallons of fuel and water that flowed into a drain used to release rainfall infiltration back into the environment.

The Navy has blamed previous spills on human error, including the 2014 release of least 27,000 gallons that touched off heightened environmental concerns. In that case, military officials blamed a contractor.

“There may well have been errors by the operators at Red Hill, but to confine the explanation simply to operator error is to ignore what is clearly issues with respect to the operation and maintenance and perhaps even the design of Red Hill,” Case said. “Operator error can be avoided by adequate design, by adequate maintenance.”

The state’s emergency order requires the Navy to defuel the tanks but allows the service to potentially refuel them at a later date if it can prove that it can safely operate the facility. However, the latest iteration of the National Defense Authorization Act includes a provision requiring the Navy to come up with alternatives to Red Hill, including potential sites outside of the state.

Ka‘ohewai, a recently formed coalition of Native Hawaiian organizations dedicated to shutting down the facility, called on the Navy to go further.

In a news release issued Tuesday, Camille Kalama, a Native Hawaiian rights attorney affiliated with the coalition, said, “The Red Hill facility should never have been built over our aquifer. To make matters worse, the Navy has failed to operate its facility safely, offered lies and half-truths about its leaks, and has prioritized convenient access to fuel above the health and safety of families.”

She continued, “We cannot afford to wait until the next catastrophe before taking active steps to permanently shut the facility down.”

Hawaii is the headquarters for U.S. Indo-Pacific Command, which oversees all U.S. military operations across the Pacific, much of the Indian Ocean and parts of the Arctic. The Pentagon considers it a top-priority theater of operations and defense spending. Additionally, it makes up at least 7.7% of Hawaii’s GDP — the second-highest rate among states.

While Hawaii’s congressional delegation has pushed for a stronger military presence in the Pacific, Kahele, an Afghan War veteran, told Navy leaders, “I want to impress on you, like we have been doing for the last two months as the united delegation, that we are at an inflection point for … the state of Hawaii’s public trust and relationship with the United States military moving forward.”