That portion of the West Fork of the South Branch of the Chicago River in Cook County, Illinois, lying between the west line (produced north) of the Collateral Channel of the Sanitary District of Chicago, in the northwest quarter of section 36, township 39 north, range 13 east, third principal meridian, and a line one thousand three hundred feet east of and parallel to the west line of section 30 (section line in South Western Avenue), township 39 north, range 13 east, third principal meridian, in the city of Chicago, Illinois, as the same now exists or may hereafter be extended, is declared to be a nonnavigable stream within the meaning of the Constitution and laws of the United States.

The right to alter, amend, or repeal this section is expressly reserved.