A decision by federal regulators could require Entergy to refund about $50 million to its more than 1 million customers in Louisiana, announced Public Service Commissioner Foster Campbell late Wednesday.

But it could take a year for a judge with the Federal Energy Regulatory Commission to calculate precisely how much money would be returned to Entergy’s customers, Campbell said the PSC’s special counsel, Michael Fontham of New Orleans told him.

At issue is the company’s “System Agreement,” in which Entergy agreed to charge all its customers in Louisiana, Arkansas, Mississippi and Texas roughly the same.

FERC found that Entergy sold cheaper energy outside its four-state system and billed its customers for more costly power, Campbell said.

“Entergy allocated the revenues from the off-system sales to its Arkansas utility, and due to special rules in place there, it was able to pocket the profits,” he said. “As a result, customers throughout the system paid more.”

Campbell, of Bossier Parish, is a Democratic candidate for the U.S. Senate in this fall’s election.