Seventy million barrels is the strict physical minimum needed at the top of the caverns to keep the extraction pipes safely submerged in oil rather than water, said Siddharth Misra, a petroleum engineering professor at Texas A&M University.

But “the practical operational floor for the crude inventory is between 250 million and 300 million barrels,” Misra said in an email to CNBC. At current inventory levels, “cavern integrity and overall operational capability are at an elevated risk,” he said.

When the inventory drops below 300 million barrels, the SPR loses its ability to pump oil at rapid speeds to address emergencies, Misra said. The system’s pipes and pumps could also get damaged as the oil layer thins at the top and sludge rises toward the extraction intake at the cavern ceiling, he said.

Fresh water is often pumped into the caverns during rapid drawdowns, which dissolves the salt walls, Misra said. This “creates flatter, less stable roof and severely thins the critical salt pillars that separate adjacent caverns, greatly increasing the geological risk of a structural cave-in,” he said.

The SPR was originally designed for five full drawdowns. Instead, it has executed dozens of large and small releases over the past 40 years, Misra said.

“Because the system was not designed for this many cycles, the repeated injection of water and extraction of oil have caused severe cavern deformation, accelerated the rate of massive salt falls from the ceilings, and significantly weakened the overall structural integrity of the aging reserve,” he said.

Energy Department officials told the GAO that they are “holding the SPR infrastructure together with ‘Band-Aids,’ and that it is uncertain how long they will hold.” More than a quarter of the SPR inventory was “not available for drawdown due to a combination of construction outages and cavern outages” as of December 2025, the GAO found.

The quotes from Misra read to me like scientists talking about climate change. They can’t say “this situation is fucked and we should probably take this seriously yesterday” because that’s not science language. So instead they say stuff like “increased risk” and “significantly weakened structural integrity”.

But basically, it sounds like many other aspects of the US. Decaying infrastructure, no long-term plans in place to sustain it, short-term thinking making the situation worse.