Our situation is... we are attempting to get permission to
Attach a finger dock on to an existing marina (moveable with water
Level). We must move the marina down 5ft which comes within 2 ft of a
Fixed dock. The fixed dock and end of marina are parallel. The
Owners of marina and fixed dock are saying that when wter rises in
Lake the marina and fixed dock will collide. Before last rain we
Measured 9ft between the two... after heavy rain (2ft added to lake)
We measured 12.5ft between. None of the dock owners believe this.
Appreciate your help.

The distance between the fixed dock and the moveable marina has nothing to do with the depth of the lake. Instead, it is dependent upon such factors as the wind, currrent, etc.

A sketch of what you are talking about would be helpful.

Please don't start a new thread to simply clarify an old one - you can use the "answer" feature to add a new post with the new information. For reference this is the original question:
https://www.askmehelpdesk.com/physics/object-movement-when-water-added-663017.html

I agree with AK_Lawyer - I still don't quite understand the geometry of what is going on here. For example - how does the "marina" rise and fall with water level - is it hinged at the shore? As it rises and falls I don't understand what would make it skew left or right to come closer to the fixed dock - please clarify that. Is the "finger dock" extension on the marina fixed? Is it at right angles to the marina or uis an extension making the marina longer? Basically the answer depends on how the marina is hinged, and how the "finger dock" is arranged relative to the fixed dock.