Unemployed miners started digging at either end of this tunnel, part of the Bureau of Reclamation's $3 million Uncompahgre Valley Project. It is 10 feet by 12 feet, 5.8 miles long, and two-thirds concrete lined, with the upstream portion cut through solid rock. It carries water from a deep gorge of the Gunnison River under Vernal Mesa to the 12-mile-long South Canal, which flows into the Uncompahgre River. From the Uncompahgre, water is channeled into a network of canals irrigating 146,000 acres in Delta, Montrose, and Ouray counties. President William Howard Taft presided at the grand opening ceremonies in 1909. As the first major U.S. transmontane irrigation system and the longest U.S. irrigation canal when built, it has been designated a National Historic Civil Engineering Landmark.