C. When a permit by rule is required as provided by rules adopted by the department, the fee is $55.

If a project described in paragraph A or B is reviewed and approved by a professional engineer at a soil and water conservation district office that has a memorandum of understanding with the department concerning review of projects pursuant to this section, the fee is reduced to $100 for the first acre of disturbed area, plus $50 for each additional whole acre of disturbed area.

13. Significant existing sources.__The department may require a person owning or operating a significant existing source of storm water to implement a storm water management system.__The owner or operator shall obtain approval from the department pursuant to this subsection for the storm water management system.

For the purposes of this subsection, "significant existing source" means a significant existing source of storm water pollution based on quantity or quality standards for storm water from a developed area that was in existence prior to July 1, 1997 and is located in the direct watershed of a waterbody that is impaired due to urban runoff.__The department shall identify significant existing sources as provided in this subsection.

A. The department shall develop a total maximum daily load for the watershed of a waterbody impaired due to urban runoff prior to designating significant existing sources within the watershed.

B. The department shall adopt rules prior to requiring that an owner or operator of a significant existing source within the direct watershed of a specific waterbody obtain approval of a storm water management system.__Rules adopted pursuant to this paragraph are routine technical rules as defined in Title 5, chapter 375, subchapter 2-A.__The rules must include, but are not limited to, the following:

(1) The name of or other means of identifying the waterbody that is impaired due to urban runoff;

(2) A list of significant existing sources or a description of the types or classes of significant existing sources;