Wish I knew the answer myself.
I was looking at a good site for Texas lakes today but can't find it now. Part of the problem of getting old.

The only thing I can think is that they take population density into the equation when they determine what lakes to release.
Arlington Lake had enough water released over the last day or so to bring it back to normal levels. Yet Joe Pool continues to increase to the point where it is just over a foot below flood pool.