1. Criminal mischief is criminal mischief in the first degree if either of the following apply:

 a. The cost of replacing, repairing, or restoring the property that is damaged, defaced, altered, or destroyed is more than ten thousand dollars.
 b. The acts are intended to or do in fact cause a substantial interruption or impairment of service rendered to the public by a gas, electric, steam or waterworks corporation, telephone or telegraph corporation, common carrier, or a public utility operated by a municipality.
 2. Criminal mischief in the first degree is a class “C” felony.