Before Pearl Harbor was attacked, the Roosevelt Administration was already worried about the vulnerability of the harbor's above-ground fuel storage tanks. In 1940, the decision was made to build something unprecedented: an underground fuel depot that could survive aerial bombardment while providing gravity-fed fuel flow directly to the fleet. Engineers surveyed the Ko'olau Range and settled on Red Hill for its homogeneous basalt geology, which could support enormous excavated chambers, and its elevation, which would allow fuel to flow downhill through 2.5 miles of tunnel to fueling piers at Pearl Harbor without pumping. The original plan called for four tanks. The final facility held twenty. Each tank could store approximately 12.5 million gallons, and three gravity-fed pipelines connected the storage caverns to the harbor. The American Society of Civil Engineers recognized it as a Historic Civil Engineering Landmark in 1995 -- a designation that acknowledged the facility's engineering ambition even as its environmental liabilities were becoming impossible to ignore.

By the late 1990s, Navy and state health officials knew that fuel constituents were appearing in the groundwater around Red Hill. Thousands of pages of reports documented the contamination. Yet officials from Honolulu's Board of Water Supply -- the agency responsible for the city's drinking water -- say they were never informed until after a major spill. The Navy began quarterly groundwater monitoring in 2005 and launched environmental investigations in 2007 to model how contaminants moved through the aquifer. A 2014 fuel release from Tank 5 prompted increased testing. Trace amounts of fuel compounds appeared near the Navy's own drinking water shaft -- 17 parts per billion, below the 100 parts per billion threshold considered concerning, but no longer zero. The numbers were small. The trend was not.

On November 20, 2021, another jet fuel leak contaminated the Joint Base Pearl Harbor-Hickam water system, which supplies approximately 10,000 civilian and military households and schools. Residents reported foul-smelling tap water with an oily sheen. Symptoms followed: nausea, diarrhea, intense headaches. By December, more than 1,000 military families had been forced from their homes. About 2,700 homes in ten communities were in the affected area. Secretary of the Navy Carlos Del Toro traveled to Hawaii and apologized directly to residents. The CDC published a study documenting self-reported symptoms lasting more than a month. The Sierra Club of Hawaii launched a campaign demanding the facility be fixed or shut down. Ernest Lau, manager of the Honolulu Board of Water Supply, stressed that the aquifers around Red Hill were critical to Oahu's entire drinking water supply -- not just the military's.

On March 7, 2022, the Department of Defense announced that Red Hill would be closed. Secretary of Defense Lloyd Austin stated plainly: "Defueling and closing Red Hill is the right thing to do -- for our service members, our families, the people of Hawaii, the environment, and our nation." A Joint Task Force, established on September 30, 2022, under Vice Admiral John F. G. Wade, was charged with safely and expeditiously defueling the facility. The task was immense -- removing 250 million gallons of fuel from tanks buried inside a mountain, connected by aging pipelines to a harbor that hosts the Pacific Fleet. Congress appropriated over $250 million for the effort. The closure marked a remarkable reversal for an installation that had been considered essential to Pacific military readiness for eight decades. In January 2025, the Navy and Defense Logistics Agency were fined $5,000 by the EPA for failing to attend a required community meeting about the cleanup -- a small penalty that underscored how the relationship between the military and the community it had contaminated remained strained long after the tanks were ordered emptied.