[RightWhale]

. A lake with 37 times that much water would have covered quite and area, too much IMO to be contained by a dam at one end.

Why not? It doesn't matter how much water is in there, just how deep it is and how wide the chokepoint is.

[Mind-numbed Robot]

It is obvious that I did not explain my point very well. What I was attempting to say is that water of that quantity would be so spread out that there would be no choke point, it would escape somewhere, even between mountain ranges.