The Retsof Mine Collapsehttp://www.livingstoncountyhistorica....com/salt-mineOn March 12, 1994 the Retsof Salt Mine, which had been in operation for over 100 years and was the largest salt mine in North America, collapsed. One of the major environmental impacts of the collapse is that the mine filled up with ground water. The combination of salt and water created a brine mixture, which eventually traveled up through shale deposits above the collapsed mine and settled in the lower aquafer, contaminating local water supplies. By the close of 1994 an estimated 20 wells were classified by the County as being dried up or completely unusable. This number continued to rise as the mine continued to flood, and additional well testing was conducted. The mine officially closed a year later.