In 1905, when the city of San Francisco lobbied Congress to allow it to dam the Hetch Hetchy Valley to provide the growing city with water, Muir and Colby were leaders of the campaign to prevent the damming of the Tuolumne River and the flooding of the valley.
During the year 1905, when San Francisco attempted to secure Congressional approval for a dam in the Hetch Hetchy Valley to provide water for its expanding population, Muir and Colby were prominent figures who opposed this project and fought to protect the Tuolumne River and its valley.