CWA means the Clean Water Act (formerly referred to as the Federal Water Pollution Control Act of Federal Pollution Control Act Amendments of 1972) Public Law 92-500, as amended by Public Law 95-217 and Public Law 95-576; 33 U.S.C. 1251 et seq.
40 CFR § 124.2
In addition to the definitions given in 122.2 and 123.2 (NPDES), 501.2 (sludge management), 144.3 and 145.2 (UIC), 233.3 (404), and 270.2 and 271.2 (RCRA), the definitions below apply to this part, except for PSD permits which are governed by the definitions in 124.41. Terms not defined in this section have the meaning given by the appropriate Act.