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Metropolitan Water Reclamation District of Greater Chicago


The Calumet-Saganashkee (Cal-Sag) Channel Watershed is located in southwestern Cook County and drains an area of 151 square miles that includes 27 communities. The area north of the Cal-Sag Channel is drained primarily by the East and West branches of Stony Creek, which both discharge into the Cal-Sag Channel. Several smaller streams discharge westward into the Illinois & Michigan (I&M) Canal or southward into the Cal-Sag Channel. The area south of the Cal-Sag Channel has various tributaries, such as Tinley Creek and Mill Creek, that flow north to the Cal-Sag Channel. Other tributaries flow west to the I&M Canal, and south west into Will County.

Stormwater infrastructure

The MWRD has more than 240 active and complete stormwater projects throughout Cook County. These improvements include regional and local stormwater projects, green infrastructure, Space to Grow, and voluntary flood-prone property acquisitions. To see what projects are active and complete in your watershed, see the map below.

Regional reservoirs

In conjunction with local municipalities, the MWRD operates three regional reservoirs located in this watershed, providing 377 acre-feet (122.8 million gallons) of stormwater detention.

  • Bedford Park Reservoir - Bedford Park, IL - 188 acre-feet
  • Melvina Ditch Reservoir - Burbank, IL - 165 acre-feet
  • Oak Lawn Reservoir - Oak Lawn, IL - 24 acre-feet

Additional infrastructure

The following MWRD infrastructure are also located within this watershed. Below, you can download a map of these facilities located throughout Cook County.

MWRD Facilities and Infrastructure Map

Tunnel and Reservoir Plan

The northernmost tip of this watershed is served by the Mainstream tunnel system and McCook reservoir, while the easternmost side of the watershed is serviced by the Calumet tunnel system and Thornton composite reservoir. The tunnels and reservoirs were constructed as part of the Tunnel and Reservoir Plan (TARP).

Wastewater treatment

Wastewater in this watershed is primarily treated by the Calumet Water Reclamation Plant, which can treat up to 430 million gallons of wastewater per day. The northern tip of the watershed is served by the Stickney Water Reclamation Plant, while the western most edge of the watershed is served by the Lemont Water Reclamation Plant.

To learn more about wastewater treatment and these facilities, please visit the wastewater treatment webpage. We also offer both virtual or in-person tours of our facilities.

Chicago Area Waterways

The Cal-Sag Channel was constructed in 1922 and is the primary receiving waterway for this watershed. It connects with the Little Calumet River in Calumet Park and flows to the Chicago Sanitary and Ship Canal in Lemont.

These rivers and canals make up a part of the Chicago Area Waterway System (CAWS). The CAWS provides drainage for much of the Chicago region and connects the Great Lakes with the Gulf of Mexico. The MWRD controls the flow and water level in the CAWS using control structures to both prevent discharges into Lake Michigan and reduce the risk of overbank flooding. These structures are located along Lake Michigan and at the southernmost point of the CAWS, the Lockport Powerhouse.

The MWRD also monitors the water quality of these waterways. In this watershed, three Sidestream Elevated Pool Aeration (SEPA) stations were installed along the CAWS to improve the water quality and support natural habitats for fish and other aquatic life.

Watershed Planning Council meetings


Cal-Sag Channel WPC

Southwest Conference of Mayors
708-701-2232 |

Cal-Sag Channel watershed council members

Bedford Park
Blue Island
Chicago Ridge
Evergreen Park
Hickory Hills
Merrionette Park
Oak Forest
Oak Lawn
Orland Hills
Orland Park
Palos Heights
Palos Hills
Palos Park
Tinley Park
Willow Springs

Opted out of WPC membership to this watershed
Bremen Township
Calumet Township
Lemont Township
Lyons Township
Orland Township
Palos Township
Unincorporated Cook County
Opted out of WPC membership to this watershed
Stickney Township
Worth Township