There are places in California where infrastructure can't help. There is just not enough water for more people.

That's not really true except perhaps on the shallowest level. There's a lot of environmental issues, pre-1914 water rights, short-term climate issues like ENSO and MJO, and crop choices that have caused California to experience water shortages. Maybe in some cases we can put crops under solar panels to save water[0], or reclaim more water through toilet-to-tap programs. You know, through infrastructure.

Reductionist statements like yours never really reflect any real-world policy environment. The real world is messy and complicated.

[0]: https://arstechnica.com/science/2019/09/crops-under-solar-pa...

To push in a different direction, there isn't enough water for more people while keeping the amount and types of agriculture in California constant. Prioritize residential water use over agricultural rather than aggressively doing the reverse, and you'd probably see improvement. Singapore and Hong Kong are very strong arguments to me against the idea that California couldn't handle more.

Lucky for us, none of these “at capacity” areas are in high cost metros like LA, San Diego or the Bay Area

No that's not correct. Have you used the transportation systems in those areas during rush hour?