40 CFR 503.3 - Permits and direct enforceability.
(a) Permits. The requirements in this part may be implemented through a permit:
(1) Issued to a “treatment works treating domestic sewage”, as defined in 40 CFR 122.2, in accordance with 40 CFR parts 122 and 124 by EPA or by a State that has a State sludge management program approved by EPA in accordance with 40 CFR part 123 or 40 CFR part 501 or
(2) Issued under subtitle C of the Solid Waste Disposal Act; part C of the Safe Drinking Water Act; the Marine Protection, Research, and Sanctuaries Act of 1972; or the Clean Air Act. “Treatment works treating domestic sewage” shall submit a permit application in accordance with either 40 CFR 122.21 or an approved State program.