As a regional government agency providing wastewater treatment and flood management services for 28 communities, the Milwaukee Metropolitan Sewerage District (MMSD) serves 1.1 million people in a 420 square-mile service area.

Established by state law, the District is governed by 11 commissioners and does have taxing authority.

In addition to its core responsibilities, MMSD also conducts and provides water quality research, laboratory services, household hazardous waste collection, mercury collection, industrial waste monitoring, and Milorganite production and marketing.