The proposed amendment consists of four principal modifications to current Subsection R317-1-3(3) and some minor formatting changes: 1) the proposed amendment allows a variance for up to five years, until 01/01/2025, for facilities that exercise "due diligence" in pursuing implementation of the TBPEL but, in spite of their diligence, would be unable to achieve the effluent limit of 1.0 mg/L total phosphorus by 01/01/2020; 2) the proposed amendment provides a waiver of up to ten years from future nitrogen regulation to dischargers who voluntarily reduce nitrogen discharges to agreeable levels prior to 01/01/2020. The goal of this waiver is to effect early, significant nitrogen reductions in discharges by facilities capable of doing so economically. Facilities that can voluntarily reduce nitrogen discharges will be able to defer major construction improvements and costs by adopting relatively minor "nitrogen optimization" improvements early. Where this waiver is employed, there will be a long-term benefit to both the receiving water quality and to the pollution control facility; 3) the proposed amendment provides clarification to the phosphorus discharge cap basis and its implementation schedule, which had not been specified in the original rule. The intent of these changes is to clarify that annual averaging over the first three years of phosphorus self-implementing monitoring will be used to establish effluent mass loading caps in pounds per day for discharging lagoon facilities; and 4) a minor modification to the requirements for manual composite sample collection and preparation is proposed as a clarification.