Waupun city officials say new phosphorous limits are resulting in significant increases in sewer bills for residents. The Waupun Common Council has approved a 7.2-percent annual increase over a four-year period, starting in April. Waupun city officials say for the average residential customer the estimated yearly increase will be around $19. By the fourth year, residents will be paying nearly $80 more than they pay now. City officials say the increase is due to mandated upgrades to the city’s wastewater treatment plant to reduce phosphorus runoff into the Rock River.