Overview of El Potosi spring, the now dry main spring of a large pluvial lake other times home of two endemic fish species, now extinct since 1996: Cyprinodon alvarezi and the monotypic Megupsilum aporus. The lake drought because of uncontrolled ground water extraction. (24°50'54"N, 100°19'24"W). Juan Miguel Artigas Azas. (17- 4月-2016).