[3] The 5.8-mile-long (9.3 km) tunnel diverts water from the Gunnison River to the arid Uncompahgre Valley around Montrose, Colorado.

At the time of its completion, it was the longest irrigation tunnel in the world and quickly made the area around Montrose into profitable agricultural lands.

Jackhammers fed by a compressor replaced hand-turned drill bits to set holes for blasting charges.

[5] The tunnel opened in 1909 to much fanfare with a dedication ceremony attended by President William Howard Taft.

[1][6] The tunnel is 5.8 miles (9.3 km) long and is 11 by 12 feet (3.4 m × 3.7 m) in cross-section, with square corners at the bottom and an arched roof.