All of that portion of the West Fork of the South Branch of the Chicago River in the county of Cook and State of Illinois, extending west from the west line of the collateral channel of the sanitary district of Chicago, in the northwest quarter of section 36, township 39 north, range 13 east, of the third principal meridian, is declared to be a nonnavigable stream within the meaning of the Constitution and laws of the United States. The right of Congress to alter, amend, or repeal this provision is expressly reserved.

The provisions of sections 401 and 403 of this title shall not apply to that portion of the west arm of the South Fork of the South Branch of the Chicago River, lying between the east line of Ashland Avenue and the north line of Thirty-ninth Street, in the city of Chicago, Illinois, as the same now exists or may hereafter be extended. All rights, authority, or control over that part of the Chicago River possessed or assumed by the United States are relinquished and abandoned, and all rights, authority, or control over the same that were possessed by the State of Illinois are fully restored to said State.

As soon as the city of Chicago, or any other governmental agency or any corporation thereunto duly authorized by the Secretary of the Army, shall have constructed, after June 7, 1924, a new channel for the South Branch of the Chicago River between West Polk Street and West Nineteenth Street in said city of Chicago, then, and in that event, so much of the channel of the South Branch of the Chicago River as shall be superseded and replaced by said new channel in accordance with the permit of the Secretary of the Army shall be discontinued and abandoned.