I am sending this in, as I recall talks I had with my deceased father.
I don't have definite times, as it happened more than once in the late 1950s early 1960s.
My father worked at a small dam called Davis Dam in Arizona on the Colorado River, across from what is now Laughlin NV.
It is between Hoover Dam and Parker Dam.
He would tell of UFOs coming at night to get power from the dam.
He and another man would be out on the top of the dam and would see the UFOs.
I don't remember if he described the shape, but probably saucer, as that is what we all thought they looked like back then.
I know there were a lot of lights on it.