BISMARCK — A Williams County judge has sided with a family whose lawsuit over oil and gas mineral rights under Lake Sakakawea reached the North Dakota Supreme Court in 2017.

An attorney for the family says he thinks the decision could impact hundreds of mineral owners with interests under Lake Sakakawea.

Northwest District Judge Paul Jacobson issued the decision late last week after the Supreme Court reversed his initial ruling and sent the case back for further consideration. In his new opinion, he concludes that “the State has no basis to continue claiming that it owns the Wilkinsons’ property."

His initial ruling sided with the state, and the family appealed.

The lawsuit, filed in 2012, centers around who owns the mineral interest under land that the federal government acquired from J.T. and Evelyn Wilkinson in 1958 as part of the Garrison Dam project. The property consists of nearly 300 acres.

The plaintiffs, who are descendants of the Wilkinsons, maintain that the family retained the mineral rights.

The state Board of University and School Lands, which manages state-owned minerals for the benefit of state schools, has disputed their ownership. It leased some of the minerals that are now being contested. The board is named as a defendant in the suit along with several oil companies.

A significant development in the legal battle occurred in 2017 when state lawmakers sought to clarify mineral ownership under Lake Sakakawea. A bill passed by the Legislature prompted a study to determine the ordinary high water mark of the Missouri River channel as it existed before the Garrison Dam. The dam flooded land along the river upstream to create Lake Sakakawea.

In remanding the Wilkinsons' case later that year, the Supreme Court said the new law “applies retroactively and the district court did not have an opportunity to consider these provisions.”

The state’s Industrial Commission adopted the study’s findings. Jacobson wrote in his opinion that the review shows that the minerals in question in the Wilkinson case fall above the high water mark. As a result, the family is entitled to those minerals, he said.

“You have a decade of production they haven’t been paid on, and there’s a lot of oil and gas wells out there,” said Joshua Swanson, an attorney representing the family. “The total dollar amount for my clients and other mineral owners is significant.”

He estimates the family is owed over $1 million in oil and gas royalties. He said the land board and Statoil, which has a lease with the state, will now have to sort out how to pay the family.

Land Commissioner Jodi Smith said the land board’s attorney is reviewing the ruling. The board plans to discuss the matter at its next meeting, on Sept. 26.

Statoil, a Norway-based oil producer, operates in the Bakken and now goes by the name Equinor. A spokesman declined to comment, citing the potential for an appeal.

Swanson said he feels confident in the family’s position if an appeal were to happen.

He said the judge's decision could affect hundreds of mineral owners with interests under Lake Sakakawea. The Wilkinson family paved the way for them, he said.

“They really were the champions carrying the banner for all these impacted mineral owners,” he said.