You can view and download the NOAA Lake Winnebago and Lower Fox River Recreational Chart map set. Click the button below and the pdf should open in your browser or you should be prompted to save it to your local device. It is 39 pages and has high level of detail thus the large file size.
The maps show some interesting features around Lake Winnebago and the Lower Fox River. The elevations through the Lock System is on page 4.