Where do you think Lake Havasu gets its water?
Thats not the point. The point is that the Colorado River water for California is drawn out of just above the Parker Dam.
Close the water off at the Hoover Dam and you close it off for AZ also.
But, I can go for shutting down the generators at the Hoover and cutting the Power for Kalifornia.
Besides that...you are about to argue with someone who lives along that river system.