Ok, seriously though. I pulled your water report (for the City). I was surprised they get their water from wells and not the lake, but I guess the wells are closer. That is a high pH, but pH is only the symptom not the cause. You need to to look at Alkalinity, Hardness, Calcium and Magnesium, among other attributes. Your Alkalinity (45ppm), Ca (14ppm), Mg (12ppm), and Hardness (83ppm) are all within acceptable ranges for nursery and even greenhouse production. Here’s a good starter guideline for those values (University of Arkansas):
https://www.uaex.edu/publications/pdf/FSA-6061.pdf
So with acceptable Alkalinity, it means that your 8.5 pH water will not have a strong impact on shifting the pH of your growing media. It has a low buffering capacity and you would not have to add much acid to lower the pH. In fact, your calcium is so low (also only a 1:1 with magnesium) that you may want experiment with ADDING calcium in the form of granular gypsum.
So why is the pH high? Hard to say, but you have elevated TDS, Chloride, Sodium, and Specific Conductance which all point to high concentrations of salts. This will mean that when you water it should be thorough enough to leach out the bottom sufficiently (which is standard bonsai practice anyway). You will also get salt buildup when your media dries out.
As for pH, you may be able to counteract it with an acid media or the addition of granular sulfur as previously suggested. I think I would go that route before getting into injecting various acids into the irrigation water. You could also ask around the nurseries to see what they do, I bet they don’t even treat their water. Of course, you’ll be keeping trees in pots quite a bit longer.
You get decent rain, so some rain tanks collecting your roof runoff can also be a good option for the dry times of the year.
Lastly, if you spray pesticides and fungicides you should check the label to see how they interact with high pH and alkalinity. It may benefit you to use distilled water when you spray.
