I think the valley should be completely restored by removing the dam. As I recall, this is the reservoir that supplies San Francsisco.
Never gonna happen. this is where SF and most of the penninsula get their drinking water from.
It has always struck me as pure hypocrisy that this rich eco-egocentrics, could fight so hard against LA, while Hetch-Hetchy remained flooded and ruined. John Muir described H-H valley as being more beautiful then Yosemite.
USACoE has been screwing with the water levels in Lake Sakakaweja up here, (Reservoir on the Missouri River in North Dakota) and the result in the low (and lower) years (it never quite seems to be filling) is the increased exposure of thick deposits of silt.
That might not seem so bad, but it takes an entire summer for this quagmire to dry enough for deer to walk out on it without getting stuck in the mud.
The county Sherrif's Dept has a hovercraft for rescuing canoeists/kayakers/boaters stuck there.
I don't know if, over the history of the reservoir, the watershed has been polluted by heavy metals or other chemicals, but if so, they would be trapped in the sediment.
Subaerial exposure and subsequent erosion of those sediments could release toxins which have been trapped there (especially heavy metals), possibly (depending on conditions) in significant amounts. No way will the valley look like it did back when, not in the next few decades, anyway.
Just a Geologist's $0.02