Nash describes how engineers in the late 1800s into the early 1900s eyed Hetch Hetchy—a valley that the Tuolumne River had carved out—as the perfect place to build a reservoir to satisfy the growing water needs of the city of San Francisco. This reservoir proposal was a subject of heated debate, as it coincided with the building momentum of the preservation movement that John Muir spearheaded. After the San Francisco earthquake and resulting fires of 1906, some of the most ardent supporters of preserving the valley in its natural state began to bend toward support for building the reservoir—including President Theodore Roosevelt. As much as Roosevelt supported conservation, he needed to consider the practical necessities of a growing San Francisco population.

The creation of a reservoir became a lightning rod. A dam would forever change the valley’s landscape, and people like John Muir saw no justification for building it. Conversely, some people, like Gifford Pinchot and others, considered the reservoir necessary. Some in the latter group, including Roosevelt himself, cared about protecting the valley but used a cost-benefit analysis to justify a reservoir; others of the latter group were unconcerned with protecting the wilderness and saw it as foolish.