567—71.11 (455B) Excavations. Approval by the department for excavations shall be required in the following instances:
	 71.11(1) Rural areas. In rural areas:
	  a.   	 Excavation in the channel on any river or stream draining more than 10 square miles where said excavation increases the cross-sectional area of said channel below bankfull stage by more than 10 percent. The cross-sectional area of the channel shall be determined based on current engineering plans, or original engineering plans, if being performed by a drainage district. If an original plan is not available, the current engineering plan will be used to determine the original cross-sectional area of the channel. The drainage district shall submit a copy of the engineering plan for increasing the cross-sectional area of a channel to the department prior to approval by the board of supervisors or trustees regardless of size of the increase. The department shall submit its decision to the drainage district within 60 days.
	  b.   	 Excavation on any flood plain of any river or stream draining more than 10 square miles where said excavation is within 100 feet of the normal stream or riverbank.
	  c.   	 Excavations in relation to highway projects are exempt except as otherwise provided for in 71.1(1), 71.1(2) and 71.1(3).
	  d.   	 Excavation for the repair and maintenance of a drainage district ditch as defined in 567—70.2(455B) is not considered an excavation within the intent of this rule if the drainage area of the ditch at the location of the proposed work is less than 100 square miles.
	 71.11(2) Urban areas. In urban areas excavations on the floodway of any stream draining more than 2 square miles.
This rule is intended to implement Iowa Code section 455B.275.