When Indianapolis Mayor Greg Ballard came into office in 2008, he inherited a wastewater treatment and sewer system that was averaging 7.8 billion gallons of overflow each year, according to federal officials. At the time, it was not unusual for as little as one-quarter to a half inch of rainfall to fill the combined sewers to capacity and flood raw sewage into local rivers and streams. Ballard also inherited a two-year-old consent decree with the U.S. Dept. of Justice to bring the city in compliance with the Clean Water Act as well as a project to expand its wastewater treatment systems that were running over budget by an estimated $300 million and months behind schedule, due in part to complex design approaches.

Although the city had built separate storm and sanitary sewers in newer neighborhoods, development over the years had lagged behind in older, densely populated areas of the city. As far back as the early 1990s, combined sewer overflows (CSOs) were a problem for local streams during extended wet weather.