A. The valuation of all electric transmission, electric distribution, gas distribution, combination gas and electric transmission and distribution, and transmission and distribution cooperative property that is subject to valuation for tax purposes shall be determined in the manner prescribed by this section except for:

1. The property of member-owned nonprofit electric distribution cooperatives.

2. Renewable energy equipment that is valued pursuant to section 42-14155.

B. Electric transmission, electric distribution, gas distribution, combination gas and electric transmission and distribution, and transmission and distribution cooperative property shall be valued as follows:

1. The department shall determine the original plant in service cost.

2. The original plant in service cost shall then be reduced by:

(a) The related accumulated provision for depreciation.

(b) The reduction in value caused by a state or federal governmental order prohibiting total or partial physical use of electric transmission, electric distribution, gas distribution, combination gas and electric transmission and distribution, and transmission and distribution cooperative property for periods of more than six months. Any reductions in value caused by a total or partial prohibition of the physical use of the property shall not exceed the cost of the restricted property less accumulated depreciation.

3. The department shall not value contributions in aid of construction.

C. The value of construction work in progress is fifty per cent of the amount spent and entered on the taxpayer’s accounting records as of December 31 of the preceding calendar year as construction work in progress.

D. The value of materials and supplies is the total cost of such property as of December 31 of the preceding calendar year.

E. The value of environmental protection facilities that are required by law is fifty per cent of the depreciated cost of the facilities.

F. All terms and applications of terms shall be interpreted according to the federal energy regulatory commission uniform system of accounts for electric and gas utilities in effect on January 1, 1989.

G. For the purposes of this section, unless the context otherwise requires:

1. "Construction work in progress" means the total of the balances of work orders for an electric transmission, electric distribution, gas distribution, combination gas and electric transmission and distribution, and transmission and distribution cooperative plant in process of construction on December 31 of the preceding calendar year, exclusive of land rights and licensed vehicles.

2. "Depreciation" means straight line depreciation over the useful life of the item of property.

3. "Distribution cooperative" means a member-owned nonprofit electric distribution cooperative corporation that is organized under or becomes subject to Title 10, Chapter 19, Article 2 or title 10, chapters 24 through 40.

4. "Electric transmission, electric distribution, gas distribution, combination gas and electric transmission and distribution, and transmission and distribution cooperative property" means plant, construction work in progress, materials and supplies and environmental protection facilities.

5. "Environmental protection facilities" means the acquisition or construction cost of any building, structure, equipment, facility or improvement that is designed and constructed solely to control, reduce, prevent or abate:

(a) Discharges or releases into the environment of gaseous, liquid or solid substances, heat or noise.

(b) Any other adverse impact of an activity on the environment.

6. "Materials and supplies" means the cost, including sales, use and excise taxes, and transportation costs to point of delivery in this state, less purchases and trade discounts, of all unapplied material and supplies on hand in this state as of December 31 of the preceding calendar year.

7. "Original plant in service cost" means the actual cost of acquiring or constructing property including additions, retirements, adjustments and transfers, but without deducting related accumulated provision for depreciation, amortization or other purposes.

8. "Plant" means all property that is situated in this state and that is used or useful for the transmission or distribution of electric power or distribution of natural gas. Plant does not include land rights, materials and supplies and licensed vehicles.

9. "Transmission cooperative" means a member-owned nonprofit electric transmission cooperative corporation that is organized under or becomes subject to Title 10, Chapter 19, Article 4.