Damages to be paid by the condemner for any property including parts of or easements across rights-of-way of a public utility or a railroad taken through the exercise of the power of eminent domain shall be ascertained and determined as provided in sections 76-704 to 76-724, except that if it is sought to condemn the property, or such part thereof as will result in a decrease in the territory or volume of service, of a public utility engaged in the rendition of existing service, such damages shall be ascertained and determined as provided in sections 19-701 to 19-707 and 70-650 or the Municipal Natural Gas System Condemnation Act, when applicable.