^ I did say "southern Marin", and Alpine Lake is north of Larkspur, making that northern Marin in my book.
The apes were specifically said to have their territory in Muir Woods which featured in both films. The lakes and dams on the map are adjacent to Muir Woods. Seems pretty solid to me, regardless of whether you consider it north or south Marin.
Considering most of Southern California is mountains or desert that would dry up rather quickly without a continuous water supply infrastructure, and most of Central California wouldn't have easy access to the ocean for major fishing expeditions needed to feed the colony, and since you'd have a whole city to scavenge for food, supplies, fuel, and shelter, San Francisco seems like an ideal location to me. The climate concerns are mild compared to much of the rest of the country.The absurdity of setting up a post-apocalyptic colony in SF is definitely the bigger stretch.![]()
Also, there's the fact mentioned in the film that the city housed major National Guard posts/armories (where they got all their weapons, ammo, and armored vehicles) and FEMA relief camps during the spread of the disease (since SF was ground zero for the Simian Flu, it's reasonable to assume it got more attention than other areas) and in the aftermath where civilization broke down and humans fought among themselves.