"Standard of Performance" means a standard promulgated by the Administrator under Section 306 of the CWA for the control of the discharge of pollutants reflecting the greatest degree of effluent reduction that the Administrator determines to be achievable through the application of the best available demonstrated control technology, processes, operating methods, or other alternatives, including, where practicable, a standard permitting no discharge of pollutants.
Ill. Admin. Code tit. 35, § 301.400