The first point that needs to be emphasized in that the plant is a water purification plant. It is not a waste water treatment facility. That is, it is used to purify the water from the canal as opposed to treating sewage. Consequently, I have never noticed any strange smells or sounds from the plant that would reduce my family's standard of living or have raised concerns about property values &/or environmental safety.
The second point that I will make is based on my experience having lived adjacent to the plant for just under 10 years. I have never had a better neighbor. Those water storage tanks never make a sound and this is the quietest neighborhood I have lived in while in Arizona.
For those of you who might question what I am saying, I agree with Craig, ask the people who live adjacent to the plant and hear what they have to say.