Iowa Admin. Code r. 561-17.7
Every producible well shall be identified by a sign, posted on the derrick or not more than 20 feet from the well. Such signs shall be of durable construction and the lettering thereon shall be kept in a legible condition and shall be large enough to be legible under normal conditions at a distance of 50 feet. The wells on each lease or property shall be numbered in nonrepetitive, logical, and distinctive sequence, unless some other system of numbering was adopted by the owner prior to the adoption of these rules. Each sign shall show the number of the well, the name of the lease (which shall be different or distinctive for each lease), the name of the lessee, owner, or operator, the permit number, and the location by quarter, section, township, and range. The signs shall be displayed for each drilling well when so required by the department.
Iowa Admin. Code r. 561-17.7