The construction forces met and overcame almost every difficulty ever encountered in tunnel excavation. Gas, cave-ins and subterranean springs interposed obstacles throughout the work. At one time a heavy flow of carbon dioxide, or choke damp, forced the workmen to flee for their lives and delayed operations until a ventilating shaft 680 feet deep was sunk. The heavy flows of hot and cold water necessitated the use of large pumps for months at a time. For more than 500 feet the tunnel was driven through a remarkable bed of fossils, consisting of the shells of extinct sea creatures, many of which were of great size. Exposed to the air, disintegration was rapid, and the huge masses of falling rock imperilled the lives of the workmen.
Notwithstanding the extraordinary care of the Government to safeguard the employees, a heavy toll of human lives was taken. The excavation work was projected from four adits, three on the Uncompahgre side and one in the canyon, and crews of drill men and assistants simultaneously began boring into the mountain from both sides. When the last charge of dynamite had been exploded and the tunnel was “holed” through, it was found that the line was true within a fraction of an inch.
Connecting with the outlet of the tunnel is a large cement-lined canal which conveys the water to the valley ten miles below. Here it mingles with the Uncompahgre, and by means of a complex distribution system of canals and laterals, finally reaches the irrigable lands.
The Uncompahgre Valley is one of exceptional scenic beauty, and is blessed with a fertile soil adapted to the growing of a wide variety of products. Its irrigable area is approximately 100,000 acres, more than half of which is now producing two generous harvests.
The discharge of the Uncompahgre River was quite inadequate for the irrigable lands in the valley, which had been brought under the ditches constructed before the passage of the reclamation act, and failure of crops occurred frequently during the low water periods. In addition there were thousands of acres of desert land in the valley doomed to aridity unless the water supply could be supplemented. The Gunnison River, flowing uselessly in its profound canyon on the other side of the range, was drawn upon by means of the tunnel, and an abundance of water is now assured for all the lands included in this project. Agriculture here is exceedingly diversified, and in many sections, is intensive. The products of the soil range include alfalfa, cereals, sugar beets, potatoes, onions, peas, beans, and other vegetables, peaches, pears, and apples. Surrounding the valley are vast areas of fine grazing lands included in national forests, which furnish summer pastures for thousands of cattle and sheep. The rapid settlement of the farm lands has been followed by a corresponding growth of the towns of Montrose, Delta and Olathe.