Underwater property boundary
First question would be, what caused the rise in water elevation. Second would be, is the survey you are following truly original or a first and what time of year was it performed? Third question is, what does the original GLO map look like if in a PLSS state? If the water body was meandered originally and then during a time of serious drought or human altered low water the surveyor you are following set the corner out there then chances are your clients boundary has been seriously altered. Historical aerials and high water mark data are where you need to search now as well as a cause unusually for high water.
I surveyed a local property about 15yrs ago where a lake shore had been altered by one land owner that had taken a backhoe and dug out a neighbors pond to where it now has a couple hundred feet of shoreline for his cattle to drink from the lake.
Also, when a lake fills up onto another's property, that neighbor automatically gains access by boat to the entire lake.
What was done was very evident by common sense. That common sense knowledge does very little in court as evidence. Without a witness to testify to the fact or film or pictures of the wrong, the neighbor gets the access free.
Just because a called for monument falls in the water of pond, it does not automatically cause his ownership boundary to move to the center of the pond.
I would imagine that it would fall relatively where the original deed bearing and distance puts it.
Is this a seasonal fluctuation? Any chance if you go back in August it will be high & dry?
What Mike Marks said. Witness corners on shore with ties to submerged corners. 😎
That is common practice in Fl. Some spring fed lakes can be 50' deep or more depending where they are. 😎