Who owns the property that consists of the easment between water and
land that is called the chicago river bank.North,South and main
branch?

Howdy captmcm-ga,

Ownership of the banks of the Chicago River belongs to the Metropolitan Water
Reclamation District of Greater Chicago (MWRDGC).
http://www.mwrd.org/

"Description of the MWRDGC"
http://www.mwrd.org/ga/budget/2005%20citizen's%20budget/Description.htm

"The Metropolitan Water Reclamation District of Greater Chicago (District) is
an independent government and taxing body encompassing approximately 91% of the
land area of Cook County, Illinois.

The District was originally organized as the Sanitary District of Chicago in
1889 under an act of the Illinois General Assembly.  The enabling act in 1889
was in direct response to a typhoid and cholera epidemic which killed thousands
of city residents. The District reversed the flow of the Chicago and Calumet
River Systems to divert contaminated water from Lake Michigan, where it could
be diluted as it flowed into the Des Plaines River and eventually the
Mississippi River.  Prior to the District?s construction of a 70.5-mile system
of canals and waterway improvements, the Chicago and Calumet River Systems were
tributary to Lake Michigan.  These river systems are now flow to the Illinois
River system."

As the controlling agency for the Chicago River, so goes the ownership of the
banks of the river, all part of water reclamation system.

If you need any clarification, please feel free to ask.

Search strategy:

Google search on: "Chicago River" water district
://www.google.com/search?q=%22Chicago+River%22+water+district

Looking Forward, denco-ga - Google Answers Researcher

I think you will have to ask at the Cook County Clerk's office:
http://www.suffredin.org/general/general.asp?pageid=9

Scroll down and click on "How can I find out who owns a piece of property?"

This site may also be of use:
http://www.chicagoareahousing.org/FaqDetail.asp?id=HOWDOIFI52&newlayout=

IF you click on the zoning map, you will see that there is various
zoning for the river banks at the confluence of the north and south
branches of the Chicago River, suggesting that the various parcels are
privately owned, not public land, as I interpret the map.

I hope this is some help, perhaps to a Researcher who can use the sites better.