The calamus is an awesome sand bottom lake. Beware late in the summer when the water drops, but you can still launch a boat. There are launches in several places around the lake. As some grumpy people mentioned, yes, you do need a park sticker, but you can get them in Burwell at the pump n pantry or at the park office right after you turn off the highway. Not a big deal at all.
Other things…good camping, good fishing, great scenery. Be safe and have fun!