I'm a bit puzzled by the term "vegetation line." If somebody clears
away the plants on their property on the south side of the river,
does that change the state line? What if they put a building
partially over the water and partially over dry land? What if, say, a
cypress tree were to grow in the middle of the river? Or
is "vegetation line" a term that just means "dry land" or "point
where vegetation *might* grow?"

Adam