Thanks for asking your relatives about this.
I have family buried there also.
I have not been to the cemetery. But I have looked at maps of the area and I do not see any body of water that would interfere with the cemetery location.
Unless it was a small creek close by that caused some of the graves to be under water, then I have no idea why it was thought the cemetery became under water.
One particular grave that was mentioned was Jessie Bryant Green. The info said that his grave was not moved when some of the others were (due to water).
He died in 1952, so if there is any credence to this info, then the relocation of some of the graves would have to be after 1952.
Other than the statement mentioned in the book of the McLeroy family history (McLeroy family married into the Green family), I have been unable to find any mention of graves having to be relocated in this cemetery.
Most likely this was one of those family recollections that was in error, as many family recollections seem to get facts mixed up at times.
So, thanks again for taking the time to ask about this and post a response.