Open space is not available for public use. we have thousands of acres in Sonoma county that are off limits. The government already controls millions of acres in the west. Some sates, that majority of their land is federally owned/controlled.
I can’t think of any open space on the peninsula, east bay, or South Bay that is off limits to public use. The only lands down here closed to the public are city owned watersheds which is utterly ridiculous. East Bay MUD land is open to public use and there are no problems. There is some irrational fear in SF and SJ that people will harm the watershed.