Attached is the Iowa Code 321.423 relating to use of a blue light by fire department members. As 321.423 (3)(2) states, the chief of the department issues the permit allowing a member to display a blue light. This is done on a form provided by the department. The Iowa DOT has a form available, Form 411022, that can be obtained only by calling them or attached is a template you can use to put on department letterhead that accomplishes the same thing.