40 CFR § 104.4 - Statement of basis and purpose.
Whenever the Administrator publishes a proposed effluent standard, the notice thereof published in the Federal Register shall include a statement of the basis and purpose of the standard or a summary thereof. This statement shall include:
(a) The purpose of the proposed standard;
(b) An explanation of how the proposed standard was derived;
(c) Scientific and technical data and studies supporting the proposed standard or references thereto if the materials are published or otherwise readily available; and
(d) Such other information as may be reasonably required to set forth fully the basis of the standard.