The springs first emerged to the surface during the lower Cretaceous period, as a result of a shift in the nearby Balcones Fault. (Fossilized dinosaur footprints are evident in the rocks near the south dam.)
The springs were considered sacred by the Tonkawa Native American tribe who inhabited the area, and were used for purification rituals. Spanish explorers first discovered the springs in the 17th century, and around 1730 erected temporary missions at the site (later moving to San Antonio).
Soon after the incorporation of the city of Austin, William ("Uncle Billy") Barton, for whom the springs are currently named settled the area in 1837, and named the three separate springs after his three daughters: Parthenia, Eliza and Zenobia. Barton died in 1840. He and subsequent owners of the property recognized its value as a tourist attraction, and promoted it vigorously, thus leading to the swimming hole's lasting popularity.
The last person to privately own the property, Andrew Jackson Zilker, deeded it to the city of Austin in 1918. During the 1920s, the city installed dams to make the swimming hole more like a conventional pool, and also installed cement walls around the inside of the pool and sidewalks around its perimeter.
The pool has been closed to the public several times starting in the 1980s due to an unsafe level of fecal coliform (E. coli) bacteria in its waters. The source of contamination is still a matter of debate; many point to upstream urban development as the cause, although high bacteria levels were first noted in the 1950s, when development in the area was rare. The contamination is worst after heavy rains.
The environmental conditions of the springs gave birth to a local political movement called the "Save Our Springs Alliance" (SOS), which later became a decades-long force in Austin municipal politics, leading to many "green" initiatives involving a multitude of environmental issues in addition to those at the springs.
Another environmental issue involving the springs and the pool emerged with the discovery of the Barton Springs salamander, a rare animal which only exists in the pool and a few surrounding environs. After some debate, and studies by the city of Austin, Texas state agencies and the U.S. Fish and Wildlife Service, it was determined that swimmers and salamanders could co-exist (as they had probably been doing for some time).
The pool is drained periodically for cleaning of excess algae which makes the rocks and side walls in the pools slippery, creating a safety hazard.
History
Environmental issues
External links