[erikm88]

Does anyone have formulae to determine what the hydrostatic pressure would be relative to the rise in water level??

[Darksheare]

I don't, but there are engineering types here that may.
And if they don't know it, they know who to grab it from.

[IonImplantGuru]

Does anyone have formulae to determine what the hydrostatic pressure would be relative to the rise in water level??

As measured at the base of the damn, pressure would rise ~1 psi for every 2 ft of level increase. I.e., level rises 10 ft, pressure rises ~5 psi.