Yes Hetch Hetchy Reservoir is inside Yosemite Park and it is owned by the City of San Francisco. Water goes from Hetch Hetchy all the way to San Francisco in a pipeline, versus a canal. Because of this San Francisco has some of the best drinking water in the State.
But funny thing about Hetch Hetchy. The Hetch Hetchy valley (that is now under water) is said by some to have been as spectacular as Yosemite Valley. Lots of people did not want the dam built. There has been a movement in recent years to drain the lake and remove the dam and restore the valley. It is estimated that it would cost the City of San Francisco and the other users of this water, about a billion dollars to restore the valley and to locate and construct another source for their water. Without getting into too much detail, we all know the politics of San Francisco and a lot of the residents there are the main protestors against building any other reservoirs in California. Yet when it comes to restoring this valley and them having to pay for it, well they are all against that. There was a recent measure on the ballot in San Francisco regarding draining Hetch Hetchy. I think it was just some type of an advisory measure and it may have provided funds to study the issue. That ballot measure was overwhelming defeated by the voters of San Francisco.
Now I'm far from an enviro whacko and I want to see more dams built in California, but I also believe Hetch Hetchy Reservoir never should have been built and now it should be drained. There are many other places dams could be built that would not destroy that type of landscape.