ELKHART – The Cimarron National Grassland this week extended an emergency closure order on a portion of grasslands in Morton County after tests to determine what killed seven cattle in the area late last year were inconclusive.

Officials extended the closure on four sections of land – or about 2,600 acres that include the Stirrup Oil Field, located along the Cimarron River Corridor north of Rolla – through Dec. 31, or unless it is otherwise rescinded before then.

“This extension is necessary to complete the assessment of safety measures that may be required to ensure public safety,” a release from the agency stated.

The Morton County Grazing Association leases the 108,000-acre grassland each year for grazing. Association range riders found the seven cattle dead toward the end of October. Six of the animals were together, Cimarron National Grassland District Ranger Lance Brown previously reported. The federal agency that manages the property then issued the emergency closure order Dec. 18.

The livestock owners had a necropsy performed on the animals and a veterinarian determined in December that the animals had inhaled something that caused them to die.

“Investigations into the specific cause of cattle deaths have been determined inconclusive,” the agency release stated. “However, safety measures are currently being developed to ensure public safety and public awareness to potential hazards associated to oil/gas operations. After successful implementation of safety measures are in place, the order will be rescinded.”

The News was unable to reach Brown for additional information.