Finally, Evans Plunge (named after its builder Fred Evans), was built in 1890 over the numerous small, sparkling springs and one Mammoth spring of mineral water. Originally, Evans Plunge and the other mineral baths in Hot Springs were sought as a cure-all for a multitude of illnesses.

"They (the springs) were the resort of the Indians long before the white man found his way into the jealously guarded realms of the Black Hills, and were considered by the red man as a panacea for all ills. This water has been found useful in the treatment of chronic diseases of the gastro-intestinal tract, diseases of the liver and biliary passages, and in rheumatism and arthritic joint disturbances, gout, and others." quote from Mineral Water in the United States by Dr. W.E. Fitch.