There are many people that use the water from Eldorado Natural Springs, that being said i know there laws (especially during droughts that prevent from recycling your own water (showers, rain catcher tubs etc.) and as stated pretty much water in the state is "owned" by someone downstream.
However, according to Aravada Brewing owner, he never has to had any minerals to his water (city not sure about well), unless you are trying to match a specific water chemistry