I'm a fairly new boat owner and have been curious about drawdown since I heard that Nickajack and Guntersville remain constant year round. Here is a few good articles for anyone else wondering the same thing.
https://www.tva.com/river/neighbors/pdf/fall99.pdf
http://www.tva.gov/rrsc/pdf/annualcycle.pdf
https://www.tva.com/river/neighbors/pdf/fall99.pdf
http://www.tva.gov/rrsc/pdf/annualcycle.pdf