WikipediaPlacer County Big Trees Grove is a small, isolated giant sequoia grove located along Mosquito Ridge Road in the American River watershed of Tahoe National Forest, California. It is known for being the northernmost and furthest removed of all giant sequoia groves. The grove contains six old-growth...
https://en.m.wikipedia.org/wiki/Placer_County_Big_Trees_Grove
I’m pretty sure it’s the northernmost grove
The next closest groves outside of Calaveras are the groves in Yosemite I think