How much of the original Northern California Pomo language still exist?

According to THIS page,

“There were once seven distinct Pomo languages, as different from one another as the Romance languages of Europe (French, Spanish, Italian, Portuguese, and so on.) Language loss in California has been especially severe, however—the legacy of the Gold Rush days, in which massacres and Indian slavery, while technically illegal, were not actively discouraged—and today the only Pomoan languages with more than a few elderly speakers are Kashaya and Central Pomo. Though the remaining native speakers of Central Pomo are also elders, there is an active language preservation movement and some young Pomos are working to learn their ancestral language before it disappears. ”

There are many other results with information about the languages, (e.g., a dictionary ) by doing a web search for “pomo language”.