It shall be the duty of the unit operator to make and file all necessary ad valorem tax renditions and returns with the proper taxing authorities covering all property of each working interest owner used or held by the operator in the unit operations. All such property of the several working interest owners shall be assessed and taxed together as a single unit. If such property is not reported for taxation by the unit operator, assessment and taxation of the working interest owners’ property of the unit shall be made as a unit by the county assessor. All such ad valorem taxes shall be paid by the unit operator initially as a part of the costs of unit operations with each working interest owner’s share thereof to be the same as other costs of unit operations. Each working interest owner shall pay or cause to be paid all production, severance and other taxes that may be imposed upon or in respect of the production of that owner’s share of the unitized substances.