Mont. Code Ann. § 10-3-1218

An owner or agent of the owner of a hazardous material involved in an incident, a person causing an incident, a person transporting a hazardous material involved in an incident, and a person owning or occupying property involved in an incident shall assist the state as requested by the incident commander in responding to an emergency situation associated with the incident as may be necessary to address an acute threat to public health or safety or to the environment until the incident commander declares that the emergency situation is over.