POINT REYES NATIONAL SEASHORE, Calif. — Seen from a nearby hilltop, the Drakes Bay Oyster Company is a cluster of shacks with faded white walls. One patched roof appears at risk of being blown away by the next Pacific squall. A dozen workers on a small weather-beaten dock were busy handling a batch of oysters harvested on a recent morning, separating the mollusks on a single rusty conveyor belt.

But this modest, family-run business just north of San Francisco lies at the center of an increasingly convoluted battle pitting longtime allies against one another and uniting traditional foes. Its fate — whether Drakes Bay will be allowed to remain on public land here or forced to close, as demanded by the federal government — has drawn the attention of a little-known, well-financed watchdog group in Washington, a United States senator from Louisiana, Tea Party supporters, environmentalists, sustainable-food proponents and celebrity chefs.

Ken Salazar, the secretary of the interior, decided against extending the oyster farm’s lease in November, and gave the Lunnys, the owners, 90 days to shut down. The Lunnys and their supporters sued, eventually winning a reprieve from a federal appeals court to continue operating until mid-May; the court is expected to decide then whether the lawsuit can move forward.

With the deadline looming, the battle has only intensified. On Friday, Representative Doc Hastings, a Washington State Republican who is chairman of the House Natural Resources Committee, addressed a letter to Mr. Salazar requesting documents related to his decision and questioning its basis. A couple of weeks earlier, Alice Waters, the owner of Chez Panisse in Berkeley, Calif., and the pioneer of the locavore movement, led a food group in filing an amicus brief urging the court to allow the farm to stay in business.

Patricia Unterman, co-owner of the Hayes Street Grill in San Francisco, a restaurant that serves local seafood and endorsed the brief, said the oyster farm was “such a rare and beautiful use of land and water” in an area with a long history of agriculture.

Ms. Unterman said she and other proponents of sustainable food had long enjoyed good relations with environmentalists, another powerful group in Northern California. “That’s why I was so astounded by what seemed to me a very doctrinaire and unnuanced approach to the Drakes Bay Oyster Company,” she said of the environmental groups’ opposition to the oyster farm.

Neal Desai, an associate director of the National Parks Conservation Association, a longtime opponent of the oyster farm, said he did not object to ranching in the park, which the government allows. But the oyster farm has no legal standing, he said, adding, “There are rules, there are policies and there are contracts.”

The Lunnys have kept on farming, though they have slowed down production because of the uncertainty and reduced their work force to 21 from 30. As a busload of visitors descended on the oyster shack, Kevin Lunny, who owns the farm with his siblings, said he had been taken aback by developments in the case, particularly the recent inclusion of his farm in a Republican energy bill in Congress.

Under the bill, the Energy Production and Project Delivery Act of 2013, permits for the nearly 2,000-mile Keystone XL pipeline would be expedited, the Arctic National Wildlife Refuge in Alaska would be opened for gas and oil development, more offshore drilling would be allowed — and the oyster farm’s operating permit would be extended for at least 10 years.

“Now people are saying we’re connected to right-wing groups, that we’ll have offshore drilling and it’ll be Drakes Bay Oyster’s fault that the Keystone pipeline gets built,” Mr. Lunny said. “And we’re saying: ‘Where does this come from? Oh, my gosh.’ Other groups that we may or may not agree with have taken up the cause.”

Mr. Lunny’s grandparents moved to Point Reyes in the 1940s to start a cattle ranch business that the family still runs, two decades before a national park was created here. Then in 1972, as Congress mandated that parts of the park be designated as wilderness, the federal government paid the oyster farm’s previous owners $79,200 for their property; they were allowed to continue farming for 40 more years, until last November, after which the area would become the first marine wilderness on the West Coast.

The Lunnys bought the oyster farm in 2004 and soon began lobbying to have the lease extended beyond 2012. Senator Dianne Feinstein of California, a Democrat, championed their cause, writing a bill in 2009 that gave the interior secretary the authority to extend the farm’s permit for 10 years.

Scientists at the National Park Service criticized the Lunnys’ environmental record, particularly in a 2007 report that indicated that the farm had harmed a nearby colony of harbor seals. But the Park Service backpedaled after outside scientists pointed out flaws in its research.

Cause of Action, a government watchdog group in Washington, quickly became the main supporter of the Lunnys’ lawsuit to reverse the interior secretary’s decision. Dan Epstein, the organization’s executive director, said he had been drawn to the case because of the Park Service’s problematic science, and decided to lead the lawsuit as a matter of government overreach and accountability.

“Oftentimes, the regulatory state has impacts that affect small businesses potentially more than big businesses,” he said. “The Drakes Bay Oyster Company, they’re not like a big company that can just afford to hire lawyers when dealing with government decision-making.”

Opponents of the farm, however, dismiss any talk of the little guy versus the state. Cause of Action, they say, is a stalking horse for big business interests, pointing out that Mr. Epstein once briefly worked for a charitable foundation run by Charles G. Koch, one of the two billionaire brothers who have financed many conservative causes.

Mr. Epstein said the donors to Cause of Action, which was founded in 2011 and recognized as a nonprofit in May, “choose to remain anonymous.” The organization does not receive money directly or indirectly from the Koch brothers, he said.

To opponents, suspicions of a broader agenda were fueled when a provision to save the oyster farm was included in the Republican energy bill. Senator David Vitter of Louisiana, who introduced the bill, became interested in the oyster company because of his background in investigating the Interior Department’s scientific conclusions on offshore drilling, said a spokesman, Luke Bolar.

Amy Trainer, executive director of the Environmental Action Committee of West Marin, a local group, said the farm’s inclusion in this “drill, baby, drill piece of legislation” was very “telling.”

As for Mr. Lunny, some of his new allies, especially the big-government opponents and Tea Party supporters drawn to his fight against the federal government, make him uncomfortable. He was surprised, he said, when his oyster farm ended up in an energy bill promoting the Keystone XL pipeline.

“We realize that’s not really in our best interest,” he said.

Photo Credit: Jim Wilson/New York Times