Calaveras Creek is a waterway that starts near Martinez and runs for fifteen miles to its mouth at the San Antonio River. Martinez is a small city in Eastern Bexar County near Converse Texas ten miles east of downtown San Antonio. The San Antonio River is a major waterway that originates in central Texas near San Antonio and follows a roughly southeastern path through the state It is the source of Calaveras Lake were it is dammed near Elmendorf. [1] Calaveras means skulls in Spanish.