Natural Springs
San Marcos Springs is one of the largest natural spring systems in Texas
San Marcos Springs flows from the Edwards Aquifer through limestone faults and has sustained human life in the area for thousands of years.
The springs sit about two miles northeast of the San Marcos courthouse. Water comes up through the Balcones fault zone from the Edwards Aquifer. Between 1892 and 1978, the average flow was estimated at about 4,300 liters per second. Paleo-Indians used the site at least 8,000 years ago. Spanish explorers and settlers came through in the 1700s and 1800s.
The springs feed the San Marcos River and support plant and animal species found nowhere else on Earth. Growing demand for groundwater threatens the springs. A spillway built in the 1950s created a swimming area at what is now Aquarena Springs. The ecology of the springs is a major reason water policy is closely watched in Hays County.
Source to confirm: Handbook of Texas — San Marcos Springs