The same thing happend at Alum Creek in Delaware, OH. The lake was built as a back up for Hoover Dam, not the big hoover dam, for Columbus's drinking water. Anyway a church that was built where the lake stands now burnt down and all the records of the cemetary were lost. So they moved all the graves with head stones, but back in the day a lot of people couldn't afford headstones, so when the records were lost so were the graves.
I believe it was 94 or 95 the water got real low and they were still letting boaters out and the turbualnce caused some coffins to come a float, they tried getting them out with a back hoe but a water logged coffin... you get the picture, wasn't pretty.
But that does suck about cumberland. I've gone down there every year since high school, a lot of coves and creeks will be gone. It will though be interesting to see what it looks like that low.