A salt well (or brine well) is used to mine salt from subterranean caverns or deposits by the use of water as a solution to dissolve the salt or halite deposits so that they can be extracted by pipe to an evaporation process that results in a brine or dry product for sale or use. In the 19th century, salt wells were a highly significant source of income for the operator and the government. Locating the underground salt deposits was usually based on locations of existing salt springs.
^Michigan Geological Survey (1876). Geological Survey of Michigan. Original from Harvard University: Published by authority of the Legislature of Michigan under the direction of the Board of Geological Survey. p. 171.