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Metropolitan Water Reclamation District of Greater Chicago

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Metropolitan Water Reclamation District of Greater Chicago

Metropolitan Water Reclamation District of Greater Chicago

Recovering Resources, Transforming Water

Strategic Plan

Tunnel and Reservoir Plan (TARP) Reservoir Levels

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The Metropolitan Water Reclamation District of Greater Chicago's Tunnel and Reservoir Plan (TARP)  is designed to reduce flooding, improve water quality in Chicago area waterways and protect Lake Michigan from pollution caused by sewer overflows. 

Street flooding and basement backups can still occur even when there is plenty of room in TARP. If small neighborhood sewers don’t have the capacity to carry water to the MWRD’s intercepting sewers or TARP tunnels, they may back up.  

If TARP is full, neighborhood sewers are designed to overflow to waterways.  

Learn more about the Tunnel and Reservoir Plan

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Recent News Releases

July 14, 2026

Board meetings are open to the public and can be streamed online.

July 13, 2026

Chicago is building a $12 million pilot project that will capture and temporarily store nearly 1.7 million gallons of excess stormwater in an underground detention system during heavy rainfall and gradually release it into the sewer system as capacity becomes available. The Wing Storage project — a partnership between the Chicago Department of Water Management and the Metropolitan Water Reclamation District of Greater Chicago — will be installed beneath city streets and attached to existing sewer infrastructure on Chicago’s West Side, where major storms caused severe flooding in 2023.

July 12, 2026

The Metropolitan Water Reclamation District of Greater Chicago (MWRD) expects to have two projects totaling $5 million to address odor mitigation near its Thornton Reservoir completed by the end of 2026, bringing total mitigation efforts over the past decade to $8.6 million, according to officials.

July 11, 2026

The massive Thornton reservoir, a south suburban quarry holding billions of gallons of stormwater and sewage that nearly filled up this past week, will take at least a month before it drains. Thornton is part of the Deep Tunnel flood-control system and resembles a canyon in South Holland. It takes in sewer wastewater during heavy storms that is later pumped out to the Calumet treatment plant at East 130th Street in the Far Southeast Side Riverdale neighborhood. For the first time since opening in 2015, the quarry filled to near capacity along with another flood-control reservoir known as McCook in Bedford Park.

Projects

The MWRD and Chicago Department of Water Management are partnering on two projects on the West Side of Chicago to build underground storage tanks that can contain a combined 1.7 million gallons of stormwater to mitigate local flooding.

The MWRD's Harvey Central Park Stormwater Detention Basin project will provide flood relief for the city of Harvey. This project will reduce flooding to approximately 209 homes during a 100-year storm event.

The 600-acre-foot Addison Creek Reservoir will hold 195 million gallons of storage capacity and connect with the Addison Creek Channel to protect the communities from overbank flooding.

The MWRD’s Robbins Heritage Park and Midlothian Creek Restoration Project will help address overbank flooding through a new stormwater park and pond, along with improvements to Midlothian Creek and an overflow channel that connects to the Cal-Sag Channel.

Calendar of Events

Jul

16

Board Meeting

10:30am - 12:00pm
Thursday, July 16, 2026

Jul

25

Back to School Health Fair

10:00am - 2:00pm
Saturday, July 25, 2026

Jul

31

Monitoring and Research Seminar

10:30am - 11:30am
Friday, July 31, 2026
Virtual

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