How deep is the water directly below the flood gates at Parker Dam in Arizona?

Answer 1

320 feet if silt hasn't collected too badly.
"Parker Dam is the deepest dam in the world; 73 percent of its structural height of 320 feet is below the original riverbed. Two-hundred and thirty-five feet of the Colorado riverbed was excavated before concrete was placed for the dam's foundation."
http://www.desertusa.com/colorado/parker_dam/du_parkerdam.html