Utah Code § 54-4-21
The commission shall have power to ascertain the value of the property of every public utility in this state and every fact which in its judgment may or does have any bearing on such value. The commission shall have power to make revaluations from time to time and to ascertain the value of new construction, extensions, and additions to the property of every public utility; provided, that the valuation of the property of all public utilities doing business within this state located in Utah as recorded in accordance with Section 54-4-22 of this chapter shall be considered the actual value of the properties of said public utilities in Utah unless otherwise changed after hearings by order of the commission. In case the commission changes the valuation of the properties of any public utility said new valuations found by the commission shall be the valuations of said public utility for all purposes provided in this chapter.
Utah Code § 54-4-21