567—75.5 (455B) Minimum standards for flood plain and floodway uses. Regulations established must require that structures vulnerable to flood damage be protected at the time of initial construction. The level of flood protection shall be commensurate with the flood damage potential of the use, must prevent obstruction of the floodway unless mitigating measures are taken, and must regulate or prohibit uses which result in significant public damages and costs. The following minimum standards shall be met:
	 75.5(1) All flood plain structures.
	  a.   	 Construction materials and methods shall be used which minimize flood damage potential.
	  b.   	 Minimum levels of flood protection shall be consistent with or exceed the minimum levels of flood protection in 567—Chapter 72.
	  c.   	 All structures used as dwellings shall be provided with an access which will remain passable by wheeled vehicles during Q100. But this criterion shall not apply where the department or its local designee determines that this access is not required for effective protection of life and property on the basis of the criteria for determining flood warning and response time as set forth in subrule 75.2(3).
	 75.5(2) Floodway development and uses.
	  a.   	 No building or other structure, deposit of fill, or other potential obstruction shall be allowed in the floodway if the development individually or collectively would increase the level of Q100. An analysis of the effect a development would have on flood levels shall be based on the assumption that all similarly situated landowners would be allowed an equal degree of development.
	  b.   	 Notwithstanding paragraph “a” of this subrule, a structure, associated fill, or another potential obstruction whose location in the floodway provides a substantial public benefit may be allowed if the resulting increase in flood levels is mitigated by purchase of flooding easements or execution of other appropriate agreements with the owners of property on which flooding would be increased. Examples are bridge embankments, water supply intake structures, and water wells with appurtenant fill.
	  c.   	 Any fill, structure or other potential obstruction allowed in the floodway shall be the minimum amount or size to achieve the intended purpose.