This is just a guess as I have wondered about that full pool number vs actual myself............The number was probably put in before they got slammed with all the rain up in Tennessee over the weekend that has caused them to open up 15 gates and send 146000 cfts at Gville dam. Since it is a measurement of above sea level in feet they are using ,they must have an area they are calculating rather than a small local depth height. They are working as fast as they can to lower the water back to normal pool for sure!! It has messed up a lot of gill beds down river. Before the rains in Tenn they were barely running any water thru usually between 9000cfs and 20000cfs avg. so the full pool number vs actual was not changing all that much . This makes only the second time they have had gates open since Jan first and is late for that to happen .Over all they had set a record for the length of time that the gates had been closed before they had to open them up a few days in late Jan of this year.
As of 6am this morning:4/26/2017 6 AM 595.27 567.62 145,289 .The 595.27 is above the dam and the 567.62 is the below the dam . I would think the above sea level would slowly get smaller the farther down from the dam you go.ON the other hand if the water is up 3 feet why isn't the above sea level not showing 3 ft higher?? None of this explains what you are asking does it HA! Next time I catch up with one of my TVA buds, I will try and get an explanation as they finally told me why the water runs the way it does under the bridges in the winter at times.