In this part the following words have the meanings indicated. “Industrial user” means: A person who is engaged in manufacturing, fabricating, or assembling goods; or A member of any class of significant producers of pollutants identified under regulations adopted by: The Secretary; or The Administrator of the U.S. Environmental Protection Agency. “Industrial user” does not include the federal, State, and local governments. “PFAS chemicals” means a class of fluorinated organic chemicals that contain at least one fully fluorinated carbon atom, including perfluoroalkyl and polyfluoroalkyl substances. “Pretreatment permit” means a document issued by the Department or the Department’s designee that authorizes a significant industrial user to introduce industrial wastes into a publicly owned treatment works in compliance with the pretreatment requirements under COMAR 26.08.01.01B(69). “Significant industrial user” means an industrial user that: Is subject to categorical pretreatment standards under 40 C.F.R. Part 403.6; Discharges an average of 25,000 gallons per day or more of processed wastewater to a publicly owned treatment works, not including sanitary, noncontact cooling, and boiler blowdown wastewater; Contributes processed wastewater that makes up 5% or more of the average dry–weather hydraulic or organic capacity of the publicly owned treatment works; or Is designated as a significant industrial user by the publicly owned treatment works on the basis that the industrial user has: A reasonable potential for adversely affecting the wastewater treatment plant’s operations and sewer system; or Violated a pretreatment standard or requirement. “Significant industrial user” does not include the federal, State, and local governments. “Waters of the State” includes: Both surface and underground waters within the boundaries of the State subject to its jurisdiction; That portion of the Atlantic Ocean within the boundaries of the State; The Chesapeake Bay and its tributaries; All ponds, lakes, rivers, streams, public ditches, tax ditches, and public drainage systems within the State, other than those designed and used to collect, convey, or dispose of sanitary sewage; and The floodplain of free–flowing waters determined by the Department on the basis of the 100–year flood frequency.