Took me a while to realise that those two patches of green along the river are marshes, you might want to make the colour/texture a bit more distinguishable from the forest.

You may not be bothered about the physical geography (I'm a geography nerd when it comes to mapping), but those marshes don't seem plausible to me, because the river flows straight through them, implying a free-draining area. Marshy areas occur on flat ground, with the rivers meandering through them in loops.