Cook County is split into six Watershed Planning Areas (WPAs).  Please consult the Watershed Planning Area map using the following link to determine the WPA associated with a site:

Watershed Planning Areas

Within each WPA, volume control or detention may be traded with existing supply sites.  Currently, site limitations and constraints are required to utilize off-site trading, with the exception of the Little Calumet River and Lower Des Plaines WPAs.  The Lower Des Plaines and Little Calumet River WPAs have been selected for a pilot study to allow for off-site trading with existing supply sites. Starting now through January 1, 2025, projects located within these WPAs do not need to demonstrate site limitations and constraints to be able to participate in detention and volume control trading. However, certain requirements such as providing onsite detention volume for the 10-year, 24-hour storm event and at least 50% of volume control storage must be met.

Additionally, the proposed peak runoff rates cannot exceed the existing peak runoff rates and any existing detention volume cannot be reduced. Specific requirements are outlined in Article 5 of the WMO. Please note, for an existing detention facility to qualify as a supply site, a Watershed Management Permit is required to demonstrate a new area that was previously not detained is now tributary to the detention facility. If you have a specific stormwater trading project that you would like to discuss, please contact the MWRD to arrange a pre-application meeting. Information about arranging pre-application meetings can be found here.

To date, the MWRD has issued permits and permit revisions for facilities that provide and make use of offsite detention and volume control facilities.  A summary of these permits and permit revisions is provided here.

Publicly Available Supply Sites

No Site Limitations or Constraints needed to trade volume in Lower Des Plaines River or Little Calumet River WPAs

Lower Des Plaines River
0.20 cfs/acre allowable release

There are currently no sites available for trading within this WPA.  We will update the website as supply sites become available.

Little Calumet River
0.25 cfs/acre allowable release

Site Limitations and Constraints are currently needed to trade volume in other WPAs

Calumet-Sag Channel
0.30 cfs/acre allowable release

There are currently no sites available for trading within this WPA.  We will update the website as supply sites become available.

North Branch of the Chicago River
0.30 cfs/acre allowable release

Poplar Creek
0.25 cfs/acre allowable release

There are currently no sites available for trading within this WPA.  We will update the website as supply sites become available.

Upper Salt Creek
0.20 cfs/acre allowable release

There are currently no sites available for trading within this WPA.  We will update the website as supply sites become available.