- They could take the water from the Colorado river too, if memory serves me right, it's just as clean as the lake. Water can be stored, remember? Towns could have periodic water transports from the lake and then store it in water towers and other containers, and in case of it getting in any way spoiled, boil it or otherwise treat it just to make sure. Water merchants are a thing too, it was quite a big thing in Fallout 1. Also, there's Lake New Vegas, which is just south of camp Golf, I believe it has clean water.
- Most, but not all the nukes. If radiation was so persistent, it wouldn't take much radioactive material to spoil the water in the lake, especially since it's standing water. And House could only deflect the nukes that were to hit the city proper, not the surrounding countryside, which was still hit with several warheads.
I must say I don't remember those mentions of radiation staying for longer. Care to point out who mentioned it?
The point at which you have to rely on "coulds" is the point at which the game has failed to explain its world properly. We don't see, or hear mentions of, the various towns such as Primm, or Novac, making frequent water transports to the lake/river and back, so they don't happen.
The water merchants are a thing... in the NCR, which only appeared in the mojave region 7 years ago. They COULD get their water from there, though that's never stated, but that would still leave where they got water for the 197 years before that unexplained.
Also, the water towers ARE the things providing irradiated water that I was talking about, so if they are storing their water there, they are only making it radioactive doing so.
-Not really, radiation being persistent only means it says around a long time. As we see in places like the Cottonwood Crater, and the Mesquite Mountains Crater, the radiation is still quite there. That doesn't mean it necessarily spread to the water supply. Although the fact that the NCRCF, Primm, Nipton, Novac, Nelson, Wolfhorn Ranch, and other areas in the southern half of the Mojave, do have irradiated water, shows the nukes must have effected the local underground water tables, though it apparently didn't spread to the lake/river.
According to various source, the rain still glows sometime, the water still glows sometimes, and radiation still lingers around even 80+ years after the war.
http://fallout.gamepedia.com/HUBJAKE.MSG
What do you need a Gieger counter for!? [Laughs] Though it's been 80 years or so since the bombs fell, there's still radiation around, you goof. You can't see it, never could, but it's there. Heck I'm willin' to bet you got some counts on you now. Everyone that lives in the wastes has a few RAD counts.
http://fallout.gamepedia.com/TYCHO.MSG
Had some pretty good training, and some good weapons, too. My grandfather was a Ranger way back when, and he taught my father everything he knew. Dad passed it on to me. So I know enough not to drink glowing water, so to speak.
http://fallout.gamepedia.com/VREE.MSG
Don't drink the glowing water.
http://fallout.gamepedia.com/BLADE.MSG
Have you ever seen the rain glow?
None of this should be happening 80+ years after the war if radiation decayed at the rate it does in real life.