Ten gallons or less -- that's how much crude oil state regulators think leaked from a pipeline in Cook Inlet last weekend.
The pipeline's owner, Hilcorp, has an even smaller estimate: three gallons. The oil company said that's based on the number and size of the oil sheens spotted, and the amount of oil recovered from the pipeline after the platform was shut down.
Kristin Ryan, who heads up spill prevention and response for the state, said she's fairly confident the final estimate won't exceed 10 gallons. But Ryan added pinning down exactly how much oil escaped won't be easy.
"This is always a really hot point in any response, and unfortunately it's just not an exact science. It is hard to really quantify a release. One of the main factors we use is how much of the product was recovered, and in this situation we've not recovered any product," said Ryan.
She said the state will continue reviewing the available evidence. For example, they're looking at Hilcorp's records on how much oil was in the line, and how much oil the company was able to pump out of the line into a storage tank. Divers will also inspect the pipeline when dangerous ice conditions in the Inlet dissipate.
That will factor into how the state penalizes Hilcorp for the leak. Ryan said the state has zero tolerance for oil spills so a fine is likely. But she also praised Hilcorp for how they handled the leak.
"This probably wasn't a lot of oil so that's, to us, a success story," Ryan said. "The response went correctly. The company did what it needed to do and didn't put anyone in harm's way and was able to get rid of the oil before a larger release occurred."
But Lois Epstein of the Wilderness Society said she's skeptical of Hilcorp's estimate that just three gallons of oil leaked into the Inlet. She says the pipeline is 75 feet below the Inlet's surface, so some of the oil may not have risen to the surface.
We need to know not just the initial estimate, which I think sounds suspiciously low, but we need to know what are the assumptions behind it and come to some sort of technical consensus of what the actual amount is," said Epstein.
Epstein is calling for Hilcorp to publicly release the data they're using to calculate how much oil leaked. The state's final estimate is expected in a couple of weeks.