I'm actually curious to know if there is evidence for lower groundwater supplies in western WA/OR after a water year with 80-90% of normal precipitation vs. one with 110-120% of normal. I've always assumed that the groundwater supply fully recharges in winter.
Completely different story east of the Cascades, obviously.
You have actually said as much in reference to your area. Not most of the rain... but the difference between 85 inches and 100 inches is likely not significant in terms of water supply. And in fact much of it does run off during heavy rain events when we run up our annual total as evidenced by rivers rising fast and flooding issues.