About 800,000 gallons of an oil-water mixture has spilled in the last two months at a Chevron operation in the Cymric Oil Field in California's Kern County Canyon.
Of the mixture, about 30% is oil, Chevron says, meaning nearly 240,000 gallons of crude have spilled out onto the earth.
On Friday, California's Department of Conservation ordered Chevron to immediately "take all measures" to the stop the flow and "prevent any new surface expressions" near the well site.
Don Drysdale, a spokesman for California's Division of Oil, Gas, and Geothermal Resources, told CNN that officials had a slightly different preliminary estimate of the oil spill than Chevron did. The agency is working with Chevron to collect data and zero in on exactly how much had reached the surface, he said.
California says Chevron allowed "surface expressions" of oil to occur May 10, June 8 and June 23. The state is saying that "remedial work" is necessary to "prevent damage to life, health, property, and natural resources."
According to the California order, Chevron has responded to notices from regulators about the issue. However, Chevron's responses have "contained, but not prevented" additional expressions of oil on the surface of the ground, the state says.
Chevron spotted the leak May 10 at its operation about 40 miles west of Bakersfield.
Morgan Crinklaw, a spokesman for Chevron, told CNN via email that 18,905 barrels of a "oily-water mix" had spilled into a dry streambed in the canyon. He confirmed that 70% of the mixture is water.
Crinklaw said that by July 9, "the seep has stopped flowing and the fluids are contained." He added that Chevron is "using pumps to remotely extract fluids from the containment area until regulatory agencies deem the area safe for entry and full cleanup."
So far, about 90% of the fluid is cleaned up, according to the company.
There's no evidence the leak has harmed wildlife
Chevron says it immediately notified regulatory agencies in May after discovering the leak, and "there has been no impact to waterways or wildlife."
On May 13, shortly after Chevron sounded the alarm about the leak, the California Department of Fish and Wildlife's Office of Spill Prevention and Response posted a photo of the spill on Facebook, noting that it hadn't observed any "visibly oiled" wildlife around the leak.
This year's inland spill in California is larger than a 2015 California oil spill that spewed 105,000 gallons of crude oil out of a ruptured pipeline off the coast near Santa Barbara.
However, that spill, from a pipeline owned by Plains All American Pipeline, was more ecologically harmful because it occurred near an active waterway.