The 19.1 foot bridge cannot be avoided by using the Cal Sag Channel. That bridge is a railroad bridge which used to swing but is no longer inoperable. It is located on the Illinois Waterway at mile 300.6 which is a few miles southwest (downstream) of the junction with the Chicago River. The Chicago River goes through the downtown section of Chicago and has a bridge clearance 17 feet. The Cal Sag Channel has a clearance of 20 feet. There is no water route around the 19.1 foot bridge. The water level may vary slightly depending upon rainfall, etc. It is actually a pool between dams & locks and the channel depth is maintained and used by commercial traffic. For more information visit our website at www.greatloop.com and go to the FAQs page. Eva & Ron Stob, Directors America's Great Loop Cruisers' Association P. O. Box 168, Greenback, TN 37742 865-856-7888 Fax: 865-856-7889 Website: www.greatloop.com