The portion of the west arm of the South Fork of the South Branch of the Chicago River, as established by the ordinance of the city of Chicago on July 17, 1911, in the southwest quarter of section 32, township 39 north, range 14 east of the third principal meridian, in the city of Chicago, county of Cook, State of Illinois, lying westerly of a straight line drawn from a point in south dock line of the said west arm 203.94 feet westerly of the point of intersection of the south dock line of the said west arm with the west dock line of the east arm of the South Fork of the South Branch of the Chicago River as established by said city of Chicago ordinance of July 17, 1911, measured along the south dock line of said west arm, thence to a point in the north dock line of the said west arm said point being 278 feet westerly of the intersection of the north dock line of the said west arm with the west dock line of the South Fork of the South Branch of the Chicago River as established by said city of Chicago ordinance of July 17, 1911, measured along the north dock line of said west arm of the South Fork of the South Branch of the Chicago River, is declared to be and is on and after September 1, 1959 to be regarded as a nonnavigable water of the United States within the meaning of the Constitution and laws of the United States: Provided, That plans for a suitable bulkhead to retain any fill to be placed in the waterway shall be submitted to and approved by the Corps of Engineers, United States Army, prior to the placing of such fill.