Thousands of miles of old mining tunnels surround the Bingham Canyon Mine. Unlike today's open pit, the old mines were a network of underground tunnels and shafts. The Bingham Tunnel was completed in April 1951 to provide access to the Lark and Niagara workings, or ore bodies, and its length was reported as 3.9 miles. The tunnel was used for production until Kennecott acquired it in the late 1970s, after which it was used only for water management. Water management and extraction are important for open-pit mine walls because groundwater rises through natural springs and rainwater flows into the deepest hole it can find. The Bingham Tunnel remains one of the mine's main dewatering tunnels and was updated in 2016 to maintain water flows using a mix of traditional and modern mining techniques. Subsurface water is directed through a collection system, including mining tunnels, and is either piped to the Bingham Canyon Reservoir system or treated and reused in Kennecott's operations.