I think the actual importance of Hetch Hetchy as a water resource is much overrated. SF sells much of that water, and I have seen at least one analysis that says downstream storage capacity is more than enough to take up the slack.
It almost certainly was not necessary at the time: my interpretation is that Gifford Pinchot pushed it to prove an ideological point (along with putting the Forest Service in the dept of Ag instead of Interior where it belongs) knowing full well that there were plenty of other sites for a SF water supply.
One should not assume that either the power or water would be lost either: the water and its power will still be there, and part of the plan would no doubt include ways to capture both downstream. There are plans to remove hydro sites at many other places in the PNW including all 4 PacifiCorp dams on the Klamath, with plenty of new renewable sources becoming available that are a lot more eco friendly than hydro.
San Francisco and the private developers and utilities have had a free ride at the expense of the rest of us for 100 years.
Enough already
