Rear fender area rust?

I have a rust problem with my wagon, It is the rear fender area next to the bumper. Does anybody know what I am talking about? its the small hole on the profile pic. Sorry for a lack of pictures... I was wondering if that area can be fixed with a panel, or is it part of the whole side of the car and can only be patched. Thanks!!!

Hopefully Ill get the picture situation figured out soon.

Rear quarter. Water pools there. How bad is the rust?

You can patch that, but it's not going to be cheap... and where there's one small hole, there are likely other problems. Where is it leaking from? How is it getting there? etc.

Its leaking form a hole in-between the vista roof and the rear driver's side door. Pretty bad too. That's what I think caused it, I can paste a link of the video I made If you want me to? For now I put blue tape over the hole to hopefully prevent any more water from getting in.