1850: Joseph Screech becomes the first European-American to enter Hetch Hetchy Valley and meets the Native Americans who have inhabited the valley for 6000 years.

1864: President Lincoln signs the law granting Yosemite to the State of California "to be held for public use, resort and recreation".

1870: John Muir first visits Hetch Hetchy and writes about it for the Boston Weekly Transcript.

1890: President Harrison signs the law creating Yosemite National Park, which includes the Hetch Hetchy Valley.

1903: John Muir brings President Roosevelt to Yosemite, who says that the park's treasures must be preserved "with their majestic beauty all unmarred."

1913: President Woodrow Wilson signs the Raker Act, which allows San Francisco to dam the valley and build a reservoir within it.

1914: Last Sierra Club Outing to Hetch Hetchy Valley. John Muir dies.

1923: The O'Shaughnessy Dam, named for San Francisco's City Engineer, is completed at the cost of $100 million and 68 lives.

1987: President Reagan's Interior Secretary, Donald Hodel, proposes removing the dam and restoring the valley.

2004: Environmental Defense publishes study concluding the valley can be restored without impacting water supply to the Bay Area.

2005: Restore Hetch Hetchy publishes a feasibility study on the options and costs for how the valley could be restored.

2006: California Resources Agency study authorized by Governor Schwarzenegger confirms previous studies that restoration is practical.

2012: San Francisco decides on the future of Hetch Hetchy Valley.

2014: Federal resources are allocated for restoration of the valley in time for the centenary of John Muir's death.