The Sutro Tunnel.
While there was a scarcity of water on the surface at Virginia City, there was a superabundance of it, both hot and cold, under-ground in all the mines. Levels were flooded so suddenly that oftentimes the miners narrowly escaped being drowned by the vast subterranean reservoirs that were unexpectedly tapped. Great delays in mining were caused by these floods, and to pump out the water that filled the lower levels cost immense amounts of money. Several tunnels from 1,000 to 5,000 feet in length were run into the mountain, but they were of only temporary utility, as the shafts of the mines were soon below their level. In order to overcome these water troubles, Adolph Sutro early conceived the idea of running an immense drain tunnel under the Comstock Lode from the lowest possible point. A survey was made by Mr. H. Schussler, and work was commenced on the great drain tunnel (since known as the Sutro Tunnel) October 19, 1869. It starts at the edge of the valley of the Carson River, at a point nearly east of Virginia City, and has a length of 20,145 feet—nearly 4 miles. It taps the central parts of the Comstock Lode at a depth of about 1,650 feet. The tunnel is 16 feet wide and 12 feet high. Drain flumes are sunk in the floor and over these are two tracks for horse-cars. It required nearly eight years to construct the tunnel, and the total cost was about $4,500,000. Although the leading mines had their shafts down nearly 3,000 feet before the tunnel was finished, yet it was of great use, as it saved 1,600 feet of pumping.
From the main tunnel branches were run north and south along the east side of the vein for a distance of over two miles, with which the several companies connected by drain drifts from their mines. The flow of water through the tunnel has at times been over 10,000,000 gallons in twenty-four hours. Between the mouth of the tunnel and the Carson River there are 155 feet of fall, but it has never been utilized for driving reduction works. New connections are still being made with the tunnel for drainage. Though it never paid anything near what was anticipated by Mr. Sutro, the tunnel still brings in a snug sum annually. Last year (the fiscal year that ended February 29, 1888) the receipts for royalties amounted to $237,258.33. It costs a considerable amount annually to keep the main tunnel and branches in repair. This great drain at a depth of 1,600 feet below the surface allows of Pelton water wheels being set up in the shafts of the several mines and worked under immense pressure, there being a free discharge from the wheels. At the C and C shaft of the Consolidated California and Virginia, such wheels have been put in every 500 feet from the surface down to the Sutro Tunnel level. The water used on the first wheel on the surface, in the stamp-mill, is caught up, led to the shaft, and used on the second 500 feet below, and so on down to the tunnel level, the power being brought from wheel to wheel to the surface by means of a system of steel wire cables. Thus is transmitted to the surface the power developed by the whole series of wheels.