The Hetch Hetchy debate was a dispute at the turn of the 20th century.
Certain diplomatic tactics were employed by the conservationist side to help sway the majority. This diplomacy eventually led to the damming of the valley.
The preservationists' lack of diplomacy lead to less support for their opinions.
During the debate, the conservationists had stated several predicted outcomes of the damming; few of these were true successes. These failures have led to a modern-day debate today and an "unused" supply of water for San Francisco.
Despite these impacts, the consequences of this damming have led to the birth of the modern environmental movement today and influenced the decisions of other national environmental conflicts.