The Argo Tunnel, originally called the Newhouse Tunnel (after Salt Lake City mining magnate Samuel Newhouse

Samuel Newhouse

Samuel Newhouse was a Utah entrepreneur and mining magnate.He was born in New York City of European Jewish immigrant parents and grew up in Pennsylvania. He studied law there before going to Colorado in 1879...

), is a 4.16 miles (6.7 km) mine drainage and access tunnel

Tunnel

A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

 with its portal at Idaho Springs, Colorado

Idaho Springs, Colorado

The City of Idaho Springs is a municipality in the U.S. state of Colorado that is the most populous settlement in Clear Creek County, Colorado. Idaho Springs is located in Clear Creek Canyon, in the mountains upstream from Golden, some thirty miles west of Denver...

, USA. The tunnel intersected nearly all the major gold mines

Gold mining

Gold mining is the removal of gold from the ground. There are several techniques and processes by which gold may be extracted from the earth.-History:...

 between Idaho Springs and Central City

Central City, Colorado

Central City is a home rule municipality in Clear Creek and Gilpin counties in the U.S. state of Colorado, and the county seat of Gilpin County. The city population was 515 in the 2000 United States Census...

, and is the longest such drainage tunnel in the Central City-Idaho Springs mining district.

The mines drained by the Argo Tunnel are no longer active, and the water draining out the tunnel was a source of pollution in Clear Creek until the US EPA began treating the water. Large drainage tunnels in other mining districts include the Sutro Tunnel

Sutro Tunnel

The Sutro Tunnel is a drainage tunnel connected to the Comstock Lode in Northern Nevada. It begins at Virginia City, Nevada and empties approximately 6 miles southeast the town of Dayton, Nevada....

 on the Comstock Lode

Comstock Lode

The Comstock Lode was the first major U.S. discovery of silver ore, located under what is now Virginia City, Nevada, on the eastern slope of Mount Davidson, a peak in the Virginia Range. After the discovery was made public in 1859, prospectors rushed to the area and scrambled to stake their claims...

 in Nevada

Nevada

Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

, and the Leadville Tunnel and the Yak Tunnel at Leadville, Colorado

Leadville, Colorado

Leadville is a Statutory City that is the county seat of, and the only municipality in, Lake County, Colorado, United States. Situated at an elevation of , Leadville is the highest incorporated city and the second highest incorporated municipality in the United States...

.

Although the tunnel itself is not open to the public, the associated gold ore mill and an adjacent gold mine

Argo Gold Mine and Mill

The Argo Gold Mine and Mill is a former mining and milling property consisting of a gold mine and gold mill in Idaho Springs, Colorado, built at the entrance of the Argo Tunnel. The tunnel was built between 1893 and 1910 to drain the gold mines in Virginia Canyon, Gilpin Gulch, Russell Gulch,...

 are open to public tours.

History

The Argo Tunnel was started from its southern terminus at Idaho Springs in September 1893, and reached its final length of 4.16 miles (6.7 km) in November 1910, after several pauses in the work. The actual time spent driving the tunnel was nine years and seven months. The tunnel intersected nearly all the major mines between Idaho Springs and Central City.
The tunnel was built on an incline of one-half percent, so that water from the mine workings that it intersected would drain out the entrance at Idaho Springs, rather than having to be pumped out of the individual shafts. In addition, ore cars from the mines could roll downhill to the ore mill at the tunnel entrance, rather than the ore having to be hoisted out of the shafts and trucked to mills. The tunnel was driven in a north-northwest direction, perpendicular to the predominant orientation of the gold veins. It was hoped that the tunnel would intersect previously undiscovered gold veins, but there is no record that important new ore bodies were discovered.

The tunnel operated until January 1943, when miners working on the Kansas Lode near Nevadaville

Nevadaville, Colorado

Nevadaville was a gold-mining town in Gilpin County, Colorado, United States. It was also known in the 1860s and 1870s as Nevada City. The post office at Nevadaville was called the Bald Mountain post office, to avoid confusion with other Nevadas and Nevadavilles. The community is now largely a...

 blasted into a water-filled mine working, and a large slug of water flooded out the tunnel entrance, killing the four miners. Shortly after the accident, the federal government ordered all gold mines in the US to shut down, to free men and material to mine metals considered more essential to the World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 war effort. The Argo Tunnel never reopened.

Environmental remediation

Although no longer actively used, the Argo Tunnel continued to drain acid water from the mines, and was recognized as a major continuing source of dissolved metals in Clear Creek. In May 1980, a surge of water flowed from the mine and turned the water in Clear Creek orange for some distance downstream. The temporary large increase in flow was attributed to a roof collapse somewhere within the tunnel damming a large volume of water behind it, then failing suddenly.

The US Environmental Protection Agency listed the tunnel as part of the Central City/Clear Creek federal Superfund

Superfund

Superfund is the common name for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 , a United States federal law designed to clean up sites contaminated with hazardous substances...

 site, and built a treatment system at the mouth to neutralize and remove heavy metals from the 700 gallons (2,649.8 l) per minute acid mine drainage

Acid mine drainage

Acid mine drainage , or acid rock drainage , refers to the outflow of acidic water from metal mines or coal mines. However, other areas where the earth has been disturbed may also contribute acid rock drainage to the environment...

 flow before it flows into Clear Creek

Clear Creek (Colorado)

Clear Creek is a tributary of the South Platte River, approximately long, in north central Colorado in the United States. The creek flows through Clear Creek Canyon in the Rocky Mountains directly west of Denver, descending through a long gorge to emerge on the Colorado Eastern Plains where it...

. The treatment system began operation in 1998. The water treatment plant is just west of the old ore mill.