The Federal Government provides an Electronic Code of Federal Regulations (e-CFR) on the U.S. Government Printing Office's webpage. The e-CFR is a regularly updated, unofficial editorial compilation of CFR material and Federal Register amendments produced by the National Archives and Records Administration's Office of the Federal Register and the U. S. Government Printing Office.
The following link will take you directly to the most current e-CFRs for 40 CFR Subchapter N - Effluent Guidelines and Standards.