Can you live in the Bay Area taking home 42k/year?
I did for years (also working for the state). I was living here for nearly a decade before I made more than that, in fact; as a grad student my stipend was less than $20k. I have no dependents or debts to pay off, no severe medical conditions, and my benefits were always sufficient, so it was actually very easy. I lived alone for the majority of that time, but even when I shared houses or apartments it was in relatively nice neighborhoods. (All rental, of course.) Until recently I was always living very close to where I worked. I usually had at least a little disposable income and by the time I was taking home more than $30K I was saving some of it.
That said, I live in the East Bay, not SF proper, so my rents are merely extortionate but not totally unaffordable. $42K won't go very far if you want to live in the Mission - and 10 years ago, it wasn't totally unrealistic for a (childless) grad student to have that ambition.
Honestly, from what I've seen I think senior government-employed or government-funded scientists in the Bay Area mostly get paid enough already (and I would include myself in that category until very recently). It's definitely more than we'd get in another part of the country, and we/they get to play with a lot of very cool (and very expensive) toys. But the cost of living is a huge problem for recruiting; a UC Berkeley professor of my acquaintance told me they were finding it increasingly difficult to hire new faculty because they'll never be able own a home anywhere close to Berkeley itself.