That is a Very Good question BallValve.

Where I live you hit water at 10-12 feet, When we have rain.

I install all my own ground systems, because I live in the country and they don't even maintain there PolePigs. (Transformers are Rusty and leak oil)

My tower Takes Lightning strikes on a normal basis, and I have yet to have a problem with the electronics connected to it.

Now that every thing is put in underground with PVC, You can not even rely on it for a ground.

Have a Great Day.