I've never heard of Marais Degaines but he may have meant Marais Des Cygnes, which would be a great idea. It depends on where you are and what equipment you have. Drop me a PM and I'll share some specific thoughts on the area and which pools I would try. I've spent a lot of days there.
There are other less popular places too. There are marshes around Clinton lake and Hillsdale, along the river near Atchison, and a pile of them on the Missouri side, many of which are better than anything Kansas can offer. Specifically, 4 Rivers is the best public marsh in the region and closer than some I've listed in you live in the KC area. If you have a good boat you can have very good hunts at Shell Osage as well. All the big lakes in Kansas and Missouri can have good hunting, particularly in the late season. I hunted Truman and Lay Cygne when I was younger and I've hunted The Kansas River in more recent times as well. Be careful on big bodies of water, especially if you don't have experience with them.
