Hidden River Cave is located directly beneath the City of Horse Cave in south central Kentucky. The cave which is now operated by the American Cave Conservation Association, was once the source of drinking water and hydroelectricity for the City. The cave was also commercialized from 1912 through 1943. Groundwater pollution from domestic and industrial sewage was one of the factors which led to the cave's closing in 1943. For 50 years Hidden River Cave was used as little more than an open sewer. In 1989 a new regional sewage treatment system developed by the Caveland Sanitation Authority corrected the problem. The American Cave Conservation Association relocated their national headquarters to Horse Cave in 1987 with the goal of restoring Hidden River Cave and establishing a museum and educational center at the site. Today, thousands of tourist visitors and school children annually tour Hidden River Cave and the American Cave Museum at the cave's entrance. The cave, which has been called "the greatest cave restoration success story in the United States" is now open year-round to visitors.