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.