It would turn out to be the worst California coastal spill in 25 years, spreading a shimmering sheen out to sea that eventually deposited tar balls on beaches more than 100 miles (160 kilometers) away.
But were they looking at a crime scene?
Jurors being selected Thursday in Santa Barbara County Superior Court will determine if the company that operated the pipeline that ruptured, spilling at least 123,000 gallons (465,000 liters) of crude May 19, 2015, broke any laws.
Plains All American Pipeline, based in Houston, is charged with three felonies for spilling oil on land and in state and federal waters, along with a dozen misdemeanors, including violations of fish and game laws for killing sea lions, pelicans, a loon and a dolphin.
Plains apologized for the spill and paid cleanup costs. But it has insisted the spill was an accident and not a crime.
In addition to pleading not guilty, the company put out a statement when charges were filed two years ago blaming the state attorney general and Santa Barbara district attorney for inappropriately attempting to "criminalize an unfortunate accident."
A Plains spokeswoman this week said the company doesn't discuss pending legal matters. Prosecutors also refused to comment on the trial that could take months.
Two-thirds of the original 46 counts, mostly misdemeanors charging animal deaths, have been dismissed against the company. Charges were dropped against a Plains employee accused of failing to report the spill quickly enough - a misdemeanor the company still faces for not calling a federal response center within an hour of discovering the spill.
By the time employee James Buchanan phoned the center, it had known about the spill for more than two hours from another report and had already activated a cleanup response.
Because the company, and not a person, is charged, Plains would only face fines if convicted. It wasn't clear how steep those penalties could be.
For an unrelated incident five months after the spill, the Southern California Gas Co. agreed to a $4 million settlement with Los Angeles prosecutors after pleading no contest to a single misdemeanor of failing to notify state authorities about is massive natural gas well blowout in Aliso Canyon in October 2015.
The Plains spill occurred when a severely corroded pipe ruptured several miles inland from the beach, federal inspectors found.
The Pipeline and Hazardous Materials Safety Administration cited a number of preventable errors by the company, finding it failed to prevent corrosion, didn't initially detect the rupture and responded too slowly as oil flowed toward the ocean.
Plains operators working from a Texas control room more than 1,000 miles (1,609 kilometers) away had turned off an alarm that would have signaled a leak and, unaware a spill had occurred, restarted the hemorrhaging line after it had shut down, which only made matters worse, inspectors found.
Estimates of the spill by Plains reached as much as 142,000 gallons (537,000 liters). In a final investigation report, federal regulators put the figure at 123,000 gallons (465,000 liters). Prosecutors have listed the figure at 140,000 gallons (530,000 liters).
The spill, two weeks shy of Memorial Day, closed beaches with popular campgrounds for two months and put a crimp in the local tourist economy and fishing industry.
It also crippled the local oil business because the pipeline was used to transport crude to refineries from seven offshore rigs, including three owned by Exxon Mobil, that have been idle since the spill.
Last year, Denver-based Venoco, declared bankruptcy, in part because it wasn't able to operate its platform. The state is now responsible for plugging and decommissioning Veneco's wells at an estimated cost of $58 million. That doesn't include the eventual cost to remove the enormous structure.
Plains faces a federal class-action lawsuit by fishing boat operators, the petroleum industry and oil workers who lost jobs because of the spill; and owners of beachfront properties.
In its 2017 annual report, Plains estimated costs from the spill at $335 million. That doesn't include lost revenues. It is seeking approval to repair or rebuild its corroded pipelines.
The company still faces possible fines from the U.S. government for regulatory lapses and the spill remains under investigation by federal prosecutors.
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