Argo Tunnel

Argo Tunnel
U.S. National Register of Historic Places
Colorado State Register of Historic Properties
Argo Tunnel in 2009
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Location	2517 Riverside Dr., Idaho Springs, Colorado
Area	20 acres (8.1 ha)
Built	1893 (1893)
Architect	Multiple
NRHP reference No.	78000836[1]
CSRHP No.	5CC.76[2]
Added to NRHP	January 31, 1978

The Argo Tunnel is a 4.16-mile (6.69 km) mine drainage and access tunnel with its portal at Idaho Springs, Colorado, USA. It was originally called the Newhouse Tunnel after its primary investor, Salt Lake City mining magnate Samuel Newhouse, and appears by that name in many industry publications from the time period when it was constructed. The tunnel intersected nearly all the major gold mines between Idaho Springs and Central City, and is the longest such drainage tunnel in the Central City-Idaho Springs mining district.

The mines along the Argo Tunnel are no longer active or maintained, but continue to exfiltrate ground water. The drainage from the tunnel was a major source of pollution in Clear Creek, until the U.S. Environmental Protection Agency (EPA) began treating it with a facility, built near the tunnel entrance. Large drainage tunnels in other mining districts include the Sutro Tunnel on the Comstock Lode in Nevada, and the Leadville Tunnel and the Yak Tunnel at Leadville, Colorado.

The associated gold ore mill is open to public tours. As of 2017, the tunnel's front portal was re-opened to the public and included on the tour circuit.