San Marcos br/Hays County, Texas br/29 54.057' N 97 55.234' W br/145 Spring Road br/br/Text: An important element in the development of San Marcos, the Sink Springs are a part of a system of springs in the area which feed the San Marcos River. The flow of the springs is forced by artesian pressure through the San Marcos fault. Since the late 19th century the Sink Springs, located on land once owned by Republic of Texas pioneers Thomas Jefferson Chambers and Edward Burleson, have provided water for a variety of purposes, including residential use, the irrigation of commercial farms, and the operation of a woolen mill and a dairy.