The only real concern I can see is the river leaving the lake. Someone from the river police can correct me, but that seems geologically unlikely as it is. From what I recall, lakes tend to have one outflow, but can have multiple inflows.
The split at the end of the river looks like it's making a delta, which looks fine to me (hides from the river police just in case)
Other than that, it all looks fine to me. Things are very clearly labelled or represented, it's not cluttered or overdone, and the style is very nice! *rep*