Mont. Code § 75-5-613
In furtherance of 75-5-612, a person violating a condition, limitation, standard, or other requirement established pursuant to this chapter may be served with a compliance order issued by the department. The order must specify the condition, limitation, standard, or other requirement violated and must set a time for compliance. However, in establishing a time for compliance, the department shall take into account the seriousness of the violation and any good faith efforts that have been made to comply with the condition, limitation, standard, or other requirement that has been violated. The compliance order issued under this section shall be served either personally by a person qualified to perform service under the Montana Rules of Civil Procedure or by certified mail.
§ 75-5-613, MCA