To the city council, the story sounded a little fishy. It was true that Carson City, Calif., probably still had oil of some kind. Los Angeles County had a well-documented history of being an oily place. As early as the 1850s, there were reports of enterprising folks scooping up the occasional seep of oil that rose to the surface and refining it into lamp oil. But these days the easy oil of L.A. County is long gone — especially in Carson, where the oil drilling began in the 1920s.

So how was Occidental Petroleum, which had approached the city with a set of plans for new drilling infrastructure, planning to get more? A few years ago, the company had begun reopening wells that had seemed closed for good. Now, it had announced its intention to drill 200 new ones. What, exactly, was it planning on doing differently, that other wildcatters with oily gleams in their eyes had somehow missed?

“At first they said ‘hydrofracking,’” said City Councilmember Al Robles, over the phone, with the slow, patient tones of a man who has told this story many times over the last few days. “And then there was a big public outcry. So they said, ‘Oh, we changed our mind. We’re not going to do fracking any more.’”

“Then we said, ‘You’re never ever going to do fracking?’ They said ‘Well, not ever, ever. We want to keep our options open in case it’s proven safe in the future.’”

“And then there was another public outcry. So then they said, ‘OK. We are just going to use the same techniques that we have been using at the wells that we already have. We are not going to do any different.’”

Which made Robles, and the rest of the city council, suspicious. Was it possible that Occidental had been fracking already? Was it possible that it could just come up with a new procedure that used a slightly different mix of chemicals, injected into the ground at a slightly different pressure, and call it something else?

A year earlier, a nonprofit called the Environmental Working Group (EWG) had published a report about how there was actually quite a lot more fracking going on in California than anyone had admitted. California had just passed a bill that promised to specifically regulate fracking, but before the bill was passed, EWG and Earthjustice withdrew their support, saying that the new rules had been edited so much that they were close to unenforceable.

With clearer regulations, things might have gone differently; but as things stood, the city council began to get annoyed. The city was in an ongoing struggle over a housing development built on former Shell Oil property: Residents maintained that soil tests showed elevated levels of benzene and petroleum; Shell maintained that the levels were within state standards and there was no imminent health risk. Occidental had recently announced that it was going to divide itself, spinning off its California operations into a new company. Occidental claimed this was just business, but some wondered if it was a ploy to shield the company from future lawsuits.

“I was just elected last March 2013,” said Robles.  “I have been looking into this matter and trying to separate truth from fiction. I am not a petroleum expert, but as this process was coming to a conclusion, I felt that there were just too many questions, too many unknowns, and too many opportunities for something to go wrong. We have a utility tax that the city would be deprived of. But what good is a revenue stream if our community is going to be contaminated? People say we’re anti-business, but there is nothing more anti-business than pollution. Nobody wants to relocate, expand, or start a new business in a contaminated site.”

And that is the story of how, on March 19, Carson City became the first city in California to ban oil drilling — at least temporarily. It wasn’t easy: By state law, a move like this requires a supermajority, which means that four-fifths of the city council had to vote to pass it. After 45 days, they’ll have to vote again if they want to extend it, and at that point they can extend the ban for another year, for two years maximum.

Carson isn’t the only city worried about what kind of drilling is going on in its backyard. Los Angeles is in the process of drafting its own possible ban, and Santa Cruz passed a narrower ban that deals with fracking but not related practices.

Last year, two cities in Colorado, Fort Collins and Lafayette, banned fracking, only to be sued by the Colorado Oil and Gas Association. Robles isn’t sure if that’s in Carson City’s future. The two letters that Occidental has sent to the city council so far don’t mention lawsuits; they demand that the city reconsider on the grounds that since the state is developing rules to regulate drilling and fracking, the city doesn’t have jurisdiction. But both the city attorney and California’s Division of Oil, Gas, and Geothermal Resources argue that there is no current state law that preempts a city making a call like Carson’s. “I guess in 45 days they can try to convince two of my colleagues not to support it,” said Robles, about reversing the ban. “That’s the only way.”

He pauses. “That — or they could go outside the city limits.” With horizontal drilling, you don’t need to be inside a city to get at its oil or its water table. “But I know this,” says Robles, “I know there are other cities watching us very closely to see what the outcome is.”