After seeing what I have seen when I have been in Yosemite this year and reading this SFGATE article "Yosemite's Ahwahnee hosted massive Thanksgiving feast. Unmasked guests had workers appalled.", one really has to wonder how prevalent Covid is in the park.
https://www.sfgate.com/california-parks/article/Yosemite-Ahwahnee-covid-aramark-pandemic-15809327.php