Yup - the NW post was on the interior section of the lake, on the southern bank I believe, but not too far from where the rivers intersected. The AFC post was over on the Mississippi river itself. But they were within walking distances. Missionary at the AFC post would occasionally walk over to the old NW post to teach there.
I think that the drawing was based on description provided by Zeb Pike during his 1805 visit, but would need to go back and confirm that with one of the references.
r/
MM