(1) The purpose of this subchapter is to establish effluent limitations and standards, treatment requirements, standards of performance, and other requirements for point sources discharging wastes into state surface waters. These requirements, together with the rules in subchapter 13, are adopted to discharge the responsibilities of the board under Title 75, chapter 5, parts 3 and 4, Montana Code Annotated, the Montana Water Quality Act, to adopt effluent limitations and standards, standards of performance, and treatment requirements for permits issued to point sources discharging into state surface waters. These requirements are adopted in a manner that implements the national pollutant discharge elimination system (NPDES) established under sections 301, 302, 304, 306, 307, 316, 318, and 402 of the federal Clean Water Act.