Mentioned by UponArriving
25 Best Things to Do in Yosemite National Park [2021
"Hetch Hethy is a beautiful reservoir but with a heartbreaking past. It’s a glacial valley in the northwestern part of Yosemite National Park and is drained by the Tuolumne River. Believe it or not, it was actually a valley that rivaled Yosemite Valley in its beauty but in 1923, the O’Shaughnessy Dam was completed on the Tuolumne River, which flooded the entire valley."