Why does Muir believe that the water from the Hetch Hetchy Valley is not pure?

It is full of Iron

It is full of mud

It is full of sewage

It is full of chlonne

It is full of mud.

Explanation:

Hetch hetchy environment debates occurred between 1908 and 1913. Congress debated whether to make water resources available or preserve a wilderness when growing San Francisco city. Preservationist lead by John Muir argued that hetch hetchy valley should be protected from destruction and nature should be preserve for it's beauty, this is because the hetch hetchy valley is full of mud.