Okla. Stat. tit. 68, § 2852

All gas, light, heat and power companies shall annually return to the Oklahoma Tax Commission a sworn statement showing the size and total length of pipe owned by such company and the location thereof, giving the county, city and school district; a statement of franchises held by such company from any municipal corporation in this state, the length of time the same are to run, and the conditions under which they were granted; and a statement of all buildings and other permanent improvements, pumping stations, tools, material and other personal property, and the location thereof.