State officials continue to look into whether rules or laws were broken in the decades-long practice of using salty wastewater from oil wells as a de-icer on North Dakota highways - and whether they might be able to resume that practice under certain conditions.

"Everything's being studied," Attorney General Wayne Stenehjem said after Tuesday's state Industrial Commission meeting. Stenehjem, Gov. John Hoeven and Agriculture Commissioner Roger Johnson make up the commission.

The state Transportation Department stopped using the oil field wastewater as a de-icer in early February, after the practice came under scrutiny.

State Mineral Resources Director Lynn Helms told the commission Tuesday that no state laws were broken because the laws dealing with saltwater only give the commission regulation authority. However, he acknowledged in an interview with The Associated Press that there might have been a violation of an Oil and Gas Division rule that states, "At no time shall saltwater liquids or brines be allowed to flow over or pool on the surface of the land or infiltrate the soil."

"It very well might be that even if we don't find negative environmental impacts, that language of that rule was violated," Helms told the AP.

The state Health Department this summer plans to test streams, wetlands and soil to determine whether the salty oil wastewater caused any environmental harm.

The saltwater was used as a substitute for rock salt throughout western North Dakota and farther east in the Devils Lake area, Helms said.

State officials also are working to determine whether the oil wastewater is an effective substitute for rock salt or other commercially available deicing products, Assistant Attorney General Lyle Witham said in a memo.

If officials find that to be the case, oil well saltwater might be used as a deicer under a "recycling" exception to solid waste and water pollution laws. Helms said his department would have to develop rules for record keeping and tracking its use.