Each year, around December 20th, a Nevada City, Calif., woman delivers fresh flowers to the grave of her beloved great-grandmother. Then she spends the rest of the day remembering the two men she never knew: her grandfather and great-grandfather. On Dec. 20, 1921, a crew surveying locations for the dam got caught in a flash flood and a man named John Gregory Tierney was lost forever in the raging Colorado River, the first casualty of the project. Then, on Dec. 20, 1935 — 14 years later to the day — the job site suffered its last fatal accident of the project. Patrick William Tierney, John Gregory Tierney’s only son, fell to his death from one of the two intake towers on the Arizona side of Black Canyon. The Tierney men’s deaths book-ended a project that calmed a notoriously volatile river and helped give rise to the modern Southwest.
