Jake,
Are we taking into account the "Lay of the land" as it were.
For example, one of our lakes here in NM was sooooo low, (reported 80') Now, this summer, there was enough rain in the area, to cause a 20' rise over 3 weeks, now my guess is that if we have the same amount of water flow (in and out) it would take an ever increasing amount of time (there for water) to completely fill the lake. Islands dissappear and such.
As the water rises, flows past mountains and hills and into valleys.
Humm,