• If the primary SIC code of the facility is one of those identified in the regulations, the facility is subject to the stormwater permit application requirements.
• Most states run their own NPDES stormwater permitting program through authorization from federal EPA.

The phrase “stormwater discharge associated with industrial activity” means a stormwater discharge from one of 11 categories of industrial activity defined at 40 CFR 122.26. Six of the categories are defined by Standard Industrial Classification (SIC) codes while the other five are identified through narrative descriptions of the regulated industrial activity.

If the primary SIC code of the facility is one of those identified in the regulations, the facility is subject to the stormwater permit application requirements. If any activity at a facility is covered by one of the five narrative categories, stormwater discharges from those areas where the activities occur are subject to stormwater discharge permit application requirements.

Those facilities/activities that are subject to stormwater discharge permit application requirements are:

• Category One (i): Facilities subject to federal stormwater effluent discharge standards at 40 CFR Parts 405-471
• Category Two (ii): Heavy manufacturing (e.g., paper mills, chemical plants, petroleum refineries, steel mills and foundries)
• Category Three (iii): Coal and mineral mining and oil and gas exploration and processing
• Category Four (iv): Hazardous waste treatment, storage, and disposal facilities
• Category Five (v): Landfills, land application sites, and open dumps with industrial wastes
• Category Six (vi): Metal scrapyards, salvage yards, automobile junkyards, and battery reclaimers
• Category Seven (vii): Steam electric power generating plants
• Category Eight (viii): Transportation facilities that have vehicle maintenance, equipment cleaning, or airport deicing operations
• Category Nine (ix): Treatment works treating domestic sewage with a design flow of one million gallons a day or more
• Category Ten (x): Construction sites that disturb five acres or more
• Category Eleven (xi): Light manufacturing (e.g., food processing, printing and publishing, electronic and other electrical equipment manufacturing, public warehousing and storage)

Note that Category Ten (x), construction sites that disturb five acres or more, are permitted separately through the National Pollutant Discharge Elimination System (NPDES) Stormwater Construction permit.

To determine whether a particular facility falls within one of these categories, consult the regulations at 40 CFR Part 122.

Multi-Sector General Permit (MSGP)

Most states run their own NPDES stormwater permitting program through authorization from the federal Environmental Protection Agency (EPA). Industrial facilities in those states will need to obtain NPDES permit coverage through the state.

EPA remains the permitting authority in a few states, most territories, and most tribal lands. For industrial facilities located in those areas, permit coverage is available under EPA’s 2015 Multi-Sector General Permit (MSGP).

Areas where EPA remains the NPDES permitting authority and has made the permit available for coverage include:

• Idaho, Massachusetts, New Hampshire, and New Mexico;
• The District of Columbia;
• U.S. territories except for the Virgin Islands;
• Federal facilities in Colorado, Delaware, Vermont, and Washington;
• Most Indian Country lands; and
• Other specifically designated activities in specific states (e.g., oil and gas activities in Texas and Oklahoma).