I was initially surprised that it was on the Mississippi River because I knew from other documents that he lived in the Cold Water/ Spanish Lake area which I associate with the Missouri River. I looked at that island in the water trying to find it on a map, but realized there had been a lot of floods and a major earthquake since John Graham's land grant.
I also found this map (1797-1798 in French)which shows a road (Columbia Bottoms) running parallel to the Mississippi River with houses marked. I think his house is the one closest to the confluence (above the third S in Mississippi), but I didn't know what that creek was that divided him from the other four settlers: Belhame. I don't know what it is called today, but I think I found it.
My librarian friend, Larry, happened to recall another atlas we could look at.
That was a huge help because it showed John Graham's land just below the intersection of Larimore and and Columbia Bottom AND it shows the land in proximity to Spanish Lake which hasn't changed in over 200 years unlike the river and islands.
So, I sketched it out on a current map. Fortunately there were driveways so we could pull off the road and take photos looking toward the river:
As you can see it is mostly bottom land being farmed today. For a pioneer, the location must have been heaven: plenty of hunting, trapping, fishing, farming---close to the main highways of the Missouri and Mississippi Rivers with a lot of water. Sure, it flooded every now and then.
But, on the original land grant map, I noticed what looked like a parade of hills above his name "Juan Graham" which must be the hills on the other side of Columbia Bottoms Road.
We no longer believe this John/Juan Graham to be our ancestor, but hope this information can help others in genealogy.