The Metropolitan Water Reclamation District of Greater Chicago (MWRD) has started work on a nearly $400 million expansion of the Terrence J. O’Brien Water Reclamation Plant in Skokie, Illinois. The project, known as Battery E, will increase treatment capacity and help the facility meet stricter phosphorus discharge requirements.
The expansion will add aeration and settling tanks, supporting equipment, and new treatment infrastructure. It will also introduce a biological process that removes phosphorus from wastewater using microorganisms. The O’Brien plant currently serves more than 1.3 million residents in Evanston and neighboring communities. Its treated wastewater flows into the North Shore Channel.
MWRD began construction on October 8, 2026, and expects to complete the project in approximately four years. The additional capacity will allow the district to upgrade older sections of the facility while maintaining treatment operations. MWRD has already undertaken improvements to Battery D, with completion expected in 2026, and plans to begin upgrading Batteries A, B, and C in 2031.
The investment will support compliance with phosphorus discharge limits that take effect in 2027 and tighten further in 2030. By reducing phosphorus levels in treated wastewater, the project will also help improve water quality across the regional waterway system and downstream areas of the Mississippi River basin.