Sand in the rivers
It appears the only sand is available around the lake
When you walk along the light brown area on the edge of a river, it sounds like sand, it looks like sand but there is no resource. Many tribes have made homes in the mountains to get away from it all but to get sand they have to travel all the way to the lake shore. It is pretty normal for rivers to have sand. Please include this resource on the river edges.
Regards
Zerlargal