It is all about supply and demand...the Good Lord provides supply and downstream navigation supplies the demand. Tallapoosa River on Hwy 231 between Montgomery and Wetumpka today shows the Good Lord prevails!
The low lake levels in 2007, were made much worse by the Corp of Engineers demanding extra water releases from our lake to support a stupid dredging operation downstream. That dredging was for one company which went out of business in one year. BTW, "navigation" does not exist on any portion of the Alabama, Coosa, or Tallapoosa Rivers and has not for five years. Only bass boats are lifted thru dams on the Alabama now. Corps still refers to navigation, only now it means required flow to dilute poorly functioning waste treatment plants such as Montgomery and Selma.
Considering in its early years they dropped water levels in Lake Martin by 50' and it filled every year except during droughts it is no surprise to me that it can be filled that quickly. An inch rain over a 3,000 square mile watershed is a boat load of water.....pun intended.