(1) "Commission" means the oil and gas conservation commission of the state of Colorado.
(2) "Natural gas" means gas which has been produced from the earth in its original state or such gas after the same has been processed or treated.
(3) "Natural gas public utility" means any person, partnership, corporation, or association engaged in the business of transporting, distributing, or storing natural gas within this state for ultimate public consumption and either authorized to do business in this state as a public utility or authorized to do business in this state as a natural gas company as defined in the federal "Natural Gas Act", and subject to regulations by the federal power commission.
(4) "Underground reservoir" means any subsurface sand, stratum, or formation suitable for the injection and storage of natural gas therein and the withdrawal of natural gas therefrom.
(5) "Underground storage" means the right to inject and store natural gas within and to withdraw natural gas from an underground reservoir.