HONOLULU -- Navy officials “lacked sufficient understanding” of the risks of maintaining massive fuel storage tanks on top of a drinking water well at Pearl Harbor where spilled jet fuel poisoned more than 6,000 people in 2021, a U.S. military watchdog said Thursday.

That lack of awareness came even though officials had engineering drawings and environmental studies that described the risks, the U.S. Department of Defense’s inspector general said.

The finding was among a long list of Navy failures identified by the inspector general in two reports that follow a yearslong investigation into the fuel leak at the Red Hill Bulk Fuel Storage Facility. Investigators said it was imperative for the Navy to address its management of fuel and water systems at Joint Base Pearl Harbor-Hickam and recommended that the military assess leak detection systems at other Navy fuel facilities. "The DoD must take this action, and others, to ensure that tragedies like the one in November of 2021 are not allowed to repeat,” Inspector General Robert P.

Storch said in a statement. The military built the Red Hill fuel tanks into the side of a mountain in the early 1940s to protect them from aerial attack. There were 20 tanks in all, each about the height of a 25-story building with the capacity to hold 12.

5 million gallons (47.3 million liters.) The site was in the hills above Pearl Harbor and on top of an aquifer equipped with wells that provided drinking water to the Navy and to Honolulu's mu.