(1) "Natural gas company" means every corporation, company, association, joint stock association, partnership or person authorized to do business in this state and engaged in the transportation, distribution or underground storage of natural gas.
(2) "Pipeline" has the meaning given that term in ORS 772.505 (1).
(3) "Underground reservoir" means any subsurface sand, strata, formation, aquifer, cavern or void whether natural or artificially created, suitable for the injection and storage of natural gas therein and the withdrawal of natural gas therefrom, but excluding a "pool."
(4) "Underground storage" means the process of injecting and storing natural gas within and withdrawing natural gas from an underground reservoir. [1977 c.296 §8; 1989 c.821 §5]