In the the heart of California's drought-parched Central Valley, fruit and vegetable supplier to the nation, a water district is defying a federal order to give some endangered trout a 3.9 billion gallon water ride out to sea. And it could be the first skirmish in a much wider conflict.

The Endangered Species Act protects steelhead trout, a small population of which are attempting a recovery in the Stanislaus River, which flows out of the Sierra Nevada Mountains into Modesto, in the San Joaquin Valley. So earlier this week a federal fisheries agency—it's unclear which one, and there are several—told the California branch of the Bureau of Reclamation (another water agency) that the fish needed more water to get out to the Pacific. The bureau in turn passed the order to the South San Joaquin Irrigation District, telling them to let a pulse of water through the dam on the Stanislaus.

But upon receipt, Jeff Shields, the manager of SSJID went rogue: "Whose water will be released down the Stanislaus River to satisfy the second pulse flow?" Not his, in other words.

It was the second such order in the past three weeks. The SSJID complied with the first. According to the Manteca Bulletin, a local paper that has been covering the standoff, this flushed out 15,000 acre feet of water and 23 steelhead trout. But this latest order, which would reportedly use another 12,000 acre feet to save only six fish, was too much for Shields. (Fisheries agencies haven't yet confirmed that count.)

So Lewis said no to the Bureau, and then secured legal counsel. "We tried to work with the Bureau for the last several years. We’ve sent dozens of letters and ideas about how to manage the river more prudently and other issues that we felt needed to be addressed because they were affecting our water," Shields told the Manteca Bulletin. "I understand that they’re busy and they have a river that they have to manage and water that they have to take care of, but we’re busy as well—we have water that we have to manage and people that we have to look out for as well." According to Shields, this water is better used on human interests, like agriculture and homes.

As of Friday evening, the SSJID and the Bureau of Reclamation—along with several other agencies, including the National Marine Fisheries Service, which estimates how many fish are expected to swim to sea each year—were still on the phone, trying to figure out what happens next. This is likely to open the proverbial flood gates (ahem) in a long-simmering debate over whether fish are an interest group worthy of California's precious water allocations.

The environmental argument is that steelhead trout are important to mountain ecosystems, which have downstream benefits. And the flows themselves keep the briny water from the San Francisco Bay from creeping into the Sacramento Delta. But of course California is facing a record-breaking drought, and the crops that feed the country need fresh water, too. According to Lewis Moore, a spokesperson for the Bureau of Reclamation, if the various interest groups don't resolve the issue tonight, the negotiations will continue into next week. "We are hopeful there will be a favorable response, and then everything will go back to the way it was," Moore says.

Regardless, it looks like the SSJID is geared up for a fight. In the past, courts have sided with local water districts. But for someone inclined toward apocalyptic cli-fi, this kind of standoff isn't good news.