---identifier: "/us/cfr/t40/s421.31"source: "ecfr"legal_status: "authoritative_unofficial"title: "40 CFR § 421.31 - Specialized definitions."title_number: 40title_name: "Protection of Environment"section_number: "421.31"section_name: "Specialized definitions."chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"subchapter_number: "N"subchapter_name: "EFFLUENT GUIDELINES AND STANDARDS"part_number: "421"part_name: "NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY"positive_law: falsecurrency: "2026-03-24"last_updated: "2026-03-24"format_version: "1.1.0"generator: "[email protected]"authority: "Secs. 301, 304 (b), (c), (e), and (g), 306 (b) and (c), 307 (b) and (c), 308 and 501 of the Clean Water Act (the Federal Water Pollution Control Act Amendments of 1972, as amended by the Clean Water Act of 1977) and the Water Quality Act of 1987 (the “Act”); 33 U.S.C. 1311, 1314 (b), (c), (e), and (g), 1316 (b) and (c), 1317 (b) and (c), 1318 and 1361; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; 101 Stat. 7, Pub. L. 100-4."regulatory_source: "49 FR 8790, Mar. 8, 1984, unless otherwise noted."cfr_part: "421"---
Identifier
/us/cfr/t40/s421.31
Currency
2026-03-24
Positive Law
No
Updated
2026-03-24
Chapter
Environmental Protection Agency
Authority
Secs. 301, 304 (b), (c), (e), and (g), 306 (b) and (c), 307 (b) and (c), 308 and 501 of the Clean Water Act (the Federal Water Pollution Control Act Amendments of 1972, as amended by the Clean Water A... Secs. 301, 304 (b), (c), (e), and (g), 306 (b) and (c), 307 (b) and (c), 308 and 501 of the Clean Water Act (the Federal Water Pollution Control Act Amendments of 1972, as amended by the Clean Water Act of 1977) and the Water Quality Act of 1987 (the “Act”); 33 U.S.C. 1311, 1314 (b), (c), (e), and (g), 1316 (b) and (c), 1317 (b) and (c), 1318 and 1361; 86 Stat. 816, Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; 101 Stat. 7, Pub. L. 100-4.
# 421.31 Specialized definitions.For the purpose of this subpart:(a) Except as provided below, the general definitions, abbreviations and methods of analysis set forth in part 401 of this chapter shall apply to this subpart.(b) The term *product* shall mean hot aluminum metal.(c) *At-the-source* means at or before the commingling of delacquering scrubber liquor blowdown with other process or nonprocess wastewaters.