Warren Perrin, Carlin Trahan's lawyer, points to land they believe is rightfully Trahan's, on a map in the Acadian Museum in Erath, La. Peter Moskowitz/Al Jazeera America

The state never sent a letter to the family, according to Trahan. Instead, when the family got a breakdown of their royalty check each month, they noticed a line listing “State of La.” as one of the participants in the oil deal. The state was claiming 40 of the 250 acres and siphoning off about $80,000 a month in royalties.

Trahan and his family are currently in the early stages of preparing a lawsuit against the state.

But while the diverted cash may seem wrong to Vermilion Parish landowners like Trahan, it might be perfectly legal.

One of the many laws inherited by Louisiana from its French colonizers gives the state ownership of any navigable waterways, which are defined as places where boats could theoretically pass through during the high tide of winter months. Louisiana law also links land ownership to the ownership of minerals underneath.

Perrin points out that the laws might have made more sense in France, where there are fewer wetlands, but they create problems in Louisiana, where wetlands are practically everywhere, mostly privately owned and rapidly disappearing.

According to U.S. Geological Survey data, the state has lost nearly 2,000 square miles of land since 1932 — roughly the size of Delaware.

“As global warming increases and water moves inland, what’s considered a natural navigable water body will change also,” said Sally Richardson, a law professor at Tulane University. “But the state may be claiming more now. People care about the land a lot more once there’s money involved.”

Indeed, the question of why the state is getting involved right now seems to irk residents of Vermilion Parish more than the mere existence of the arcane laws.

Trahan and others say the state never asked about their land, or claimed partial ownership of it, until oil was being produced beneath it.

There’s no easy way to know why the state claims a certain piece of land or how often it does it. A representative for Louisiana’s Office of State Lands declined to comment for this story. But experts and residents say there seems to be a pattern of the state laying stake to land only when there’s money-making potential.

“The state is not exactly consistent in when they claim land, and when there’s minerals underneath, that’s when they tend to do it,” said Mark Davis, the director of the Institute on Water Resources Law and Policy at Tulane University. “In a coast as dynamic as ours, conflict is almost inevitable.”

Beyond the initial shock of losing money, Trahan and other residents say the state’s actions don’t surprise them. They say that Louisiana’s government for decades has ignored places like Vermilion Parish, home to just under 60,000 of the state’s residents, in favor of population centers and tourist destinations like New Orleans. And they say that, given the cash-poor status of Louisiana’s government, they don’t expect the state to stop taking payments, or start better protecting wetlands, anytime soon.

Trahan, Perrin and boat captain Dronet go through the canals of the parish’s wetlands frequently, either to fish or to check out the land where Trahan owns oil. But each time their boat hums along past the simple wooden camps, the egrets and the oil wells, they’re reminded by how the land never stops shrinking.

“We don’t have enough industry, we don’t have enough people and we don’t have the economic engine for [the state] to care about it,” Dronet said. “So they just let it go.”