Brule Lake is as far as you can go. Warning though.... it is shallow and many boats get hung up on the sand in the middle of the lake... can be a lot of pushing and prying to get it going again.
Main channel is tight against the west....next to the train tracks. I've seen it at its lowest, and highest. There is a ****ty little sign past the lake that says it's the National park. 1 mile past that is a beautiful campsite with a ****ter and everything...so nice in there!