Iowa Code § 138.6
The director shall serve written notice upon the holder of the permit, by restricted certified mail, return receipt requested, specifying the manner in which the holder of the permit has failed to comply with the provisions of this chapter or any rules of the department and shall fix a reasonable time within which the objectionable condition or conditions must be removed or corrected. If the holder of the permit fails to remove or correct such objectionable condition or conditions within the time fixed by the director, the director shall revoke or suspend such permit. However, if the objectionable condition or conditions endanger the health, safety, or welfare of any inhabitants of a migrant labor camp, the director shall immediately suspend or revoke such permit.
Iowa Code § 138.6