Hey dave,
That river is a man made one, so it's probably a couple feet, if you see it you can tell it looks like a canal. But anyway, I don't think you should be worried, you really have to try hard to even get to see the river from your cabin site.
For Example, My brother was a nutball when he was 14, we rented a golf cart and we had a campsite in loop 900. And some how he mananged to get through are campsite to the river and he drove along the river, he took me one day and he the cart was up on two wheels trying to go through the terrain, it was quite a path to the river, a cart wasn't meant to be taken through, if you catch my drift, but anyway.
If you were at a campsite and not a cabin site, I would be somewhat worried. But with a cabin, the whole site is taken up by the cabin, and you really don't have an open back to the river.
Now that I think about, I stayed in loop 2500 in a cabin next to the pool, and you couldn't even tell there was a river back there.
If you have any other questions, I'd be glad to answer them.
Lance