U.S. strategic reserves are getting so low the drawdown threatens to damage the 60 underground salt caverns storing American oil

Strategic oil inventories have reached a 40-year low, and experts warn their continued depletion could damage the underground caverns where the reserves are stored.

Last week, the Strategic Petroleum Reserve (SPR) plunged below 300 million barrels for the first time since the 1980s, when the reserves were being filled, according to the Department of Energy.

That pool is expected to drain further to 243 million barrels as the U.S. releases 172 million barrels to manage severe supply disruptions and rising energy costs due to the Iran war.

Those reserves are kept in 60 salt caverns across two sites in Texas and two sites in Louisiana, each thousands of feet underground.

They have a total storage capacity of 714 million barrels.

But as oil is drained from these reserves, the integrity of the caverns may be imperiled.

“I don’t know anyone who believes we can go below 300,” Amos Hochstein, a senior energy advisor for former President Joe Biden, told CNBC on Saturday.

“I know plenty of people who think we can’t get near 300 because physically you will damage the caverns where the oil is stored.” The Department of Energy denied Hochstein’s claim that the changing inventory levels risk harming the caverns.

“The caverns are always full.

All that changes is the ratio of oil and water that is filling them,” DOE chief spokesperson Ben Dietderich told Fortune in a statement.

“President Trump and [Energy Secretary Chris Wright] are responsibly managing the SPR as the critical national security asset it was designed to be, helping stabilize oil markets and protect Americans from supply disruptions.” The health of the caverns as political ammo Both Republicans and Democrats have used the status of the caverns as political ammo on issues surrounding the SPR.

In 2025, Wright testified to the House Energy and Commerce Subcommittee on Energy that President Donald Trump’s efforts to replenish the SPR were hampered by more than $100 million in necessary repairs to the reserve’s facilities.

The restoration, he argued, was a result of the quick drawdown of reserves following the Biden administration selling nearly 200 million barrels in 2022 and 2023 to steady global energy costs amid Russian’s invasion of Ukraine.

“The immediate thing we need to do is finish the repairs on the Strategic Petroleum Reserve,” Wright said in testimony.