Humulene. I live in Spokane as well and I have a Ward lab report of my tap water, this is typical water for our area I think.
I don't use my tap water because I usually make lighter colored beers. You could however if you wanted to, just get some type of acid to drop the bicarbonate down and add some salts to suit your beer style. I recommend phosphoric acid unless your making a beer that would benefit from some sourness, in that case lactic acid or acid malt will do the trick. I use crystal geyser alpine spring water by Roxane, they have it in Rosauers, Yokes etc. here's a link to their water reports:
Find the Mt Shasta report as they have several different sources, I've only found mt. Shasta water here in Spokane. The bicarbonate level is around 60ppm +/- 5ppm. My last beer was a pale ale with an SRM of 7, it took 1.25 ml of phosphoric acid 85% to hit a mash pH of 5.4 (room temp/verified with two different mfg. meters)
I can tell you that before I started dabbling into water chemistry I had some beers that were really terrible, my darker beers were fine, the really pale ones came out VERY light colored and astringent, it was worse when using British malt vs Munich or domestic two row.
I don't want to discourage you from keeping it simple for your first all grain and using the water you have, I just wanted to let you know that if you use Spokane water maybe a dark amber or brown ale would be best to start with.