Not knowing specifically, but if it is anything like the "C-Map" chips of a few years ago, they will lack the specific and detailed info for the inland waterways.
I have an older Magellen with a Lake Winni map, and it does a nice job, but there are a few missing islands, and zero navaids (buoys).
Email them...they have always given me the best of customer service.
Here's a link to their contact page:
http://www.c-map.com/index2.html
Hope it helps, and let us know how you make out.