page_title: San Marcos Springs
section_title: Geology
hierarchical_section_title: San Marcos Springs / Geology
caption_attribution_description: Downstream from the headwaters of the San Marcos River in San Marcos, Texas, USA.
context_page_description: San Marcos Springs is the second largest natural cluster of springs in Texas. The springs are located in the city of San Marcos, Texas, about 30 miles southwest of Austin and 46 miles northeast of San Antonio.
  Although Spring Lake is highly protected, it is accessible to visitors through the Meadows Center for Water and the Environment, a program of Texas State University, which offers glass-bottom boat tours among other opportunities to explore and learn about the ecosystem.
context_section_description: The San Marcos Springs is an area of artesian outflow from the Edwards Aquifer along the Balcones Escarpment. More than 200 springs flow from three large fissures and other smaller openings in the rock.  The springs provide most of the water for the San Marcos River, which flows southward from the springs' location.
  The springs have never been known to stop flowing.  The average flow is 152 ft³/s (4,300 liters/s); the lowest recorded flow of 46 ft³/s (1,302 L/s) occurred in 1956.
  In 1849, former Republic of Texas vice president Edward Burleson built a dam just downstream from the springs; the resulting lake, known as Spring Lake, inundated the springs.
caption: Downstream from the headwaters of the San Marcos Springs, Aquarena Springs, and Spring Lake.
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