The city of Portland, Maine has undergone massive improvements in efforts to improve combined sewage and storm water overflow into the Casco Bay. The city has been steadily improving storm water management since 1989 when the Conservation Law Foundation filed suit against the city for storm-related sewage overflows.

In 1989, the city recorded discharging 1.8 billion gal of storm water and sewage discharge, however, in 2016 the city reported 318.4 million gal—an 80% decrease. While the city has been utilizing a variety of storm water management practices, the crux of the issue lies in the combined storm water and sewer infrastructure.

Part of the city’s 15-year plan adopted in 2014 will involve separating storm water and sewer runoff systems and building storm water detention basins to later treat the water.