The City of Lincoln, Nebraska Theresa Street Wastewater Treatment Facility (WWTF) has recently made several modifications to the activated sludge system to control filamentous bulking and to achieve nitrification and denitrification in compliance with anticipated discharge permit requirements. Lincoln Wastewater Engineers developed an automated system to control solids retention time (SRT) in an effort to optimize the capacity and streamline operation. The system Sludge Volume Index (SVI) has improved from an average of 309 ml/g to 179 ml/g. During test periods the activated sludge system consistently nitrified to achieve ammonia levels of less than 3 mg/L. The automated SRT control scheme appears to be an effective way to optimize system capacity.