Mono Craters Tunnel, West Portal

The 11.3 mile long tunnel was bored through the hills known as the Mono Craters to extend the reach of the Los Angeles Aqueduct into the Mono Basin. Completed in 1940, the tunnel increased the capacity of the system by about 35%. This task was made exceedingly dangerous because Mono Craters are not only the youngest mountain range in North America, largely formed in the last 10,000 years, they are recently active volcanos. Work crews digging through the mountains encountered hot and cold groundwater, deadly carbon dioxide gas, and steam, costing nearly one life per mile. While the West Portal is accessible and contains the ruins of buildings used in the construction, the East Portal lies on private land and is off-limits to the public. Remains of one of the four camps occupied during the tunnel's construction are still visible at the west side of the Mono Tunnel. For five years this was a town for workers and their families, with a peak population of over 200 people and 26 buildings.