Is this where you are talking about?
If so, this is caused by the weatherseal shrinking, and the fix is rather simple. Create slack in the bottom(where the seam is) and use the slack to fit the weatherstripping to the corner where it has pulled loose. Use adhesive to hold it in place if need be. Then, go to the junkyard and cut a piece of the weatherstripping from a junk car, cut it to size, and fit it in the gap you created at the bottom.
Here'* a thread with some good information about water: http://www.bonnevilleclub.com/forum/...ht=turtle+pond