The water reports are something that I'm somewhat used to reading as it was a once my job to monitor a community well and putting out the report was part of that. Thankfully the tests and results were done with samples we turned in to the state and I never had to go too deep into that part, only compile the report and post it. Maybe look on the report for an item called "total turbidity" as it will have some effect on the TDS. Total dissolved solids can also include weird little things like MUD! I was asked at a neighborhood meeting to explain what turbidity meant and I (being the blind fool) mentioned that it was the amount of dirt or mud in the water. Since we used wells and wells are in the ground, I kind of thought having some dirt in the water was normal. That lady sure set me straight and let everybody know I didn't have any idea what I was doing since their water came out of pipes, not the ground!
The main problem for us using the CCR is that it gives us high and low levels and sometimes average but that doesn't mean the water on any given day will match the report as it can change at different times, especially weather causes. CCR is written from a health point and only somewhat important to tank use.
The nitrate is higher than some as it is an objective to have none in drinking water but it is also not at all high enough to be a real hazard and it does happen reasonably often in areas which are heavily farmed. One of the things we are going to see come to a head is that we are polluting water faster than we are cleaning it. I might guess that you would be found in the Central Valley area but that isn't to blame the local farmers as we all live downstream from somebody and if you are on a well, the surface water is kept from entering the well directly, so that means the nitrate in your water may be from hundreds of miles away and any the local farmers add, may come out in Arizona!
I am currently near Austin, Texas and one of the big issues for the future is water. We recently had a massive flood and the treatment plants in Austin were not able to filter the dirt out and there was a several weeks long boil order. Your water has a little nitrate but you can still drink or shower in it!