The Gunnison Tunnel, constructed between 1905 and 1909, was designed to supply water to parts of western Colorado, diverting water from the Gunnison River to the Uncompahgre Valley around Montrose, Colorado. At the time of its completion, it was the longest irrigation tunnel in the world. Workers encountered a number of difficulties during the construction period, including soft ground and pockets of gas. Soft ground caused a sudden collapse that killed six workers in early 1905. Despite these obstacles, the tunnelers made good progress, achieving a record by cutting through 449 feet of granite in one month. President William Howard Taft conducted the opening on September 23, 1909, pressing the switch that released the first water. The completed tunnel, which is 30,583 feet long, 10 feet wide, and 10 feet deep at the sides, is still in operation.
*granite: 화강암