567—51.7 (455B) Excavation and processing of rock and gravel products. A water permit is required for withdrawal of more than 25,000 gallons of surface water or groundwater in one day for dewatering, washing, pugging, or use of a hydraulic dredge in connection with removal or processing of rock or gravel products. This permit requirement is subject to the following exceptions:
	  1. 	 A permit is not required for operation of a hydraulic dredge which returns all water used as a transport medium directly back into the pit from which it is withdrawn by the dredge;
	  2. 	 A permit is not required for withdrawal of water from a gravel pit or rock quarry sump pit for material washing if the wash water is discharged directly back into the pit from which it is withdrawn.