Milwaukee Metropolitan Sewerage District

In the early 1980s the plant needed extensive reworking, "this does not detract from its historic significance as a pioneering facility in the field of pollution control technology.

[4][7][8] MMSD has maintained an inline storage system (ISS) based on tunnels to store and convey wet weather flows, including combined sewage, since 1994.

The Fresh Coast Resource Center[11] (FCRC) helps southeastern Wisconsin improve the health of Lake Michigan through smart use of green infrastructure.

The FCRC assists the community by providing the inspiration, education, and tools needed to create successful green infrastructure projects.

In 2017, MMSD opened the FCRC to empower people, homeowners, businesses, nonprofits, and government to take an active role in protecting the most precious natural resource: water.

Diverting combined sewer overflows (CSOs) to waterways is an emergency measure to prevent sewage backups into basements when wastewater treatment facilities reach capacity.

[15] According to scientists at the UW-Milwaukee School of Freshwater Sciences, bacteria from CSO's only survive for up to 10 days due to the frigid temperatures of Lake Michigan.

[18] MMSD’s permit requires that CSOs be limited to no more than six overflows per year, consistent with the presumption approach in the CSO Control Policy.

[19] David Biello of Scientific American writes, "Since 1994, a more than 26-mile- (42-kilometer-) long tunnel has been keeping Milwaukee's sewage from spilling into Lake Michigan.