(A) A water quality credit for each pollutant shall:
(1) Have clearly defined units expressed as mass per unit time, or other appropriate units for those pollutants not expressible by mass, and determined in accordance with rule 3745-5-08 of the Administrative Code;
(2) Have units that are consistent with time periods and provisions used in developing a TMDL, used to determine compliance with an NPDES permit limit, or use in other regulatory requirements; and
(3) Except as provided in paragraph (B) of this rule, be generated during the same time period when they are used to comply with effluent limits or other requirements specified in an NPDES permit.
(B) In accordance with an approved water quality trading management plan, credits may be held by a trading program as part of the corrective measures required under paragraph (B)(14) of rule 3745-5-06 of the Administrative Code for addressing situations when a permittee discovers that water quality credits are insufficient to achieve compliance with an NPDES permit.