| #R001 | administrative | operational | mandatory | Facility Coverage | wastewater | The regulation covers any facility that is engaged in iron or steel manufacturing, forming, and finishing, including coke manufacturing. | Facility engaged in iron or steel manufacturing, forming, or finishing | high |
| #R002 | administrative | reporting | mandatory | Permit Incorporation | wastewater | The I&S Effluent Guidelines and Standards are incorporated into NPDES permits for direct dischargers or permits or other control mechanisms for indirect dischargers | Applicable to direct or indirect dischargers | high |
| #R003 | administrative | operational | mandatory | Subcategory Classification | wastewater | The I&S regulation applies to facilities organized into 13 subcategories: | Facility must be classified into one of the 13 defined subcategories | high |
| #R004 | operational | treatment | guidance | Alternative Oil and Grease Limitations | wastewater | The EPA restored the provision that allows the use of alternative oil and grease limitations in NPDES permits (known as the “water bubble”) | Inclusion in NPDES permits for oil and grease limitations | high |