Section 124.51 - Purpose and scope(a) This subpart sets forth additional requirements and procedures for decisionmaking for the NPDES program.(b) Decisions on NPDES variance requests ordinarily will be made during the permit issuance process. Variances and other changes in permit conditions ordinarily will be decided through the same notice-and-comment and hearing procedures as the basic permit.(c) As stated in 40 CFR 131.4 , an Indian Tribe that meets the statutory criteria which authorize EPA to treat the Tribe in a manner similar to that in which it treats a State for purposes of the Water Quality Standards program is likewise qualified for such treatment for purposes of State certification of water quality standards pursuant to section 401(a)(1) of the Act and subpart D of this part.48 FR 14264, Apr. 1, 1983, as amended at 58 FR 67983, Dec. 22, 1993; 59 FR 64343, Dec. 14, 1994