>The vast majority of the population in California doesn't live in a desert. They live in chaparral, temperate coniferous forest and mountainous biomes/climates

>The vast majority of the population in California doesn't live in a desert. They live in chaparral, temperate coniferous forest and mountainous biomes/climates. The San Francisco watershed covers 40% of California including much of the region you are speaking of. The paleoclimate research, measuring historical salinity of the Bay using carbon dated sediment cores, shows that during the Medieval warm period the San Francisco watershed averaged only 60% of the rainfall it does today.