I'll speak to that. In Alberta there is something called the base groundwater protection, and the base groundwater protection is set at a depth below which the AGS, the Alberta Geological Society, believes what they consider to be non-saline water does not exist. So below that depth, the water is considered to be saline and therefore not useful.
Below the base groundwater protection, stimulation fluids will contain different products. I'm not sure if they contain everything you mentioned, but they will contain different things. Above the base groundwater protection, you're not allowed to use toxic materials. Certainly, in coal-bed methane we use nitrogen, which is obviously not toxic.