1. Effluent limitations shall be established and enforced for point sources, including publicly owned treatment works, which require the application of the best practicable control economically achievable.
2. In the case of a discharge into a publicly owned treatment plant in existence on July 1, 1977, or federally approved prior to June 30, 1974, effluent limitations shall be established and enforced which comply with applicable pretreatment requirements or are based upon secondary treatment as federally defined.