As part of the My Wisconsin Backyard series, Milwaukee PBS recently posted a video touring the Milwaukee Metropolitan Sewerage District.

Lake Michigan, along with the city’s rivers, are hotspots for local recreation, and in an effort to show the public how these waterways are kept clean, Milwaukee PBS created and published the video, which begins 320 feet underground in MMSD’s pump room. It then shows off a massive tunnel designed to reduce sewer overflows before giving a tour of the wastewater treatment facility.

The MMSD cleans billions of gallons of wastewater annually, safeguarding natural resources and protecting public health for 28 communities in southeastern Wisconsin, according to Milwaukee PBS.

Milwaukee PBS is a non-commercial media organization based out of southeastern Wisconsin providing two high-definition television stations and four additional digital television services.

To see the tour of MMSD, watch the video below.