Very true... lots of things could have happened here, though.
-She could have fell in
-Got pushed in
-She could have even jumped
-She could have been forced onto a boat and dropped off at the island after something sinister took place (far out there)
As for the first three:
They'll be able to tell if she had been under water and how long for. I read that this place couldn't be seen from shore, and due to the weather in the area since mid-January, it's possible no one has been out in a boat before then to find her.
She could have been under water for this long, or she could have landed on the island some time ago and we wont know until an autopsy is complete. From what I understand, the temps have been in the 60s there for at least a week or so.
I get the feeling that since LE called this a suicide so early on, they didn't get very far along the river before they stopped their searches.
As far as I'm concerned, an "island" would have been a first place to check if you thought she had been in the water.
I'm from Chesterfield and I didn't even know we had islands...