BISMARCK, N.D. — A North Dakota lawmaker and former Democratic gubernatorial candidate is among those who sued the state Wednesday over a new law intended to clarify long disputed ownership of minerals under a Missouri River reservoir.

Rolla Rep. Marvin Nelson said the law is “unconstitutional and a giveaway of state resources” at Lake Sakakawea that could cost the state about $2 billion in lost revenue over time.

“Basically, this is a property dispute and in a property dispute, you go to a court to settle it, not the Legislature,” Nelson said. “It’s not a political decision who owns the mineral rights.”

Gov. Doug Burgum signed the measure last year limiting state mineral claims under the lake to a smaller area than it had claimed. Besides lot income from mineral rights, it is estimated to cost the state nearly $187 million it already has collected in oil-drilling royalty payments that must be returned.

The lawsuit filed in state district court in Fargo names Burgum and Attorney General Wayne Stenehjem as defendants. Nelson and Stenehjem, a Republican, both lost to Burgum for the state’s top executive post. Paul Sorum, a Fargo architect who ran on the GOP ticket for governor last year, also is a plaintiff in the case.

Burgum spokesman Mike Nowatzki said the governor’s office is still reviewing the lawsuit and could not comment on it.

The state and federal government, land owners and oil companies all have an interest in oil that lies under Lake Sakakawea, a 180-mile-long lake created in the 1950s when the Garrison Dam was built on the Missouri River.

Drillers first tapped crude underneath the lake about a decade ago using advanced horizontal drill techniques. But the drilling technology that allows rigs to be set up far from the shoreline also led to lawsuits due to conflicting claims of ownership of the same minerals, and a slowdown of drilling there due to the uncertainty over mineral ownership.

That uncertainty spurred lawsuits, including one that went to the state’s high court last year.

Attorneys for the William Wilkinson family argued that state illegally took the family’s mineral rights when their land was flooded by the Garrison Dam.

In that case, Stenehjem argued that the land was already part of Missouri River channel and was not “inundated” by water when Lake Sakakawea was created in the 1950s. He said that meant the state owns the minerals.

But the state Supreme Court returned the case to a lower court, and said the new law passed by the Legislature last year must be considered.

Joshua Swanson, an attorney representing the family in that case, said the new lawsuit is “problematic” for its plaintiffs because the state Supreme Court already has decided the taking of the mineral rights by the state is “unconstitutional”.

The high court, however, did not go that far, and instead said if the lower court would determine the state owns the minerals, then the “plaintiffs will be deprived of the mineral interests.”