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Barton Springs are located in Austin's Zilker Park not far from the UT campus. Don't ever try to tell someone in Austin that Barton Springs is a relatively minor Edwards Aquifer water feature! Austinites love and revere Barton Springs like no other spot.
On the far bank is Main Spring, which fills a swimming hole that Austinites regard as sacred. Here, pilgrims submit to the embrace of these cool aquamarine waters. Notice what's missing is the pilgrims. On this day in the early 1990s, the pool was closed and drained because of water quality concerns.
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Though it is an Edwards spring, a groundwater divide separates this portion of the Aquifer from the central (San Antonio) portion and the large springs in San Marcos, New Braunfels, and San Antonio. There are four main spring orifices that are the only known habitat for the Barton Springs salamander, a federally listed endangered species. These four springs are the primary discharge point for the Barton Springs segment of the Edwards Aquifer. Main Spring feeds the 750' long swimming pool. There is a dam at each end of the pool; the upper dam directs flow from Upper Spring and Barton Creek into a bypass culvert so that stormwater flows do not enter the swimming area. Old Mill Spring is just south of Barton Creek about 450' below the lower dam. The fourth spring, Eliza Spring, is adjacent to the swimming pool and is surrounded by a deep concrete ampitheatre that used to also be a swimming hole but is now reserved for the salamanders.
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The highly revered swimming hole at Barton Springs in July 2008. |
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Looking toward Main Spring from the lower end of the 750' long swimming pool. |
In this segment of the Edwards, about 85% of Aquifer recharge comes from six major surface streams that cross the recharge zone: Barton Creek, Onion Creek, Slaughter Creek, Bear Creek, Little Bear Creek, and Williamson Creek (Slade, Dorsey, and Stewart, 1986). During storm events, sinkholes and fractures in the stream bed can quickly provide large volumes of water to recharge. Dye-tracing studies have found that several preferential ground-water flow paths lead to the Springs and that the four springs do not all receive water from the same flow paths (BSEACD, 2003 and Hunt, Smith, Beery, Johns, and Hauwert, 2006). Dye-tracing studies have also revealed that underground flow velocities toward the Springs are highly variable and can be quite rapid, up to six miles per day (Hauwert, Samson, Johns, and Aley, 2004). Swimmers notice that waters in the pool can become quite cloudy and turbid after rain events.
In January 2003 the
pool was closed for 90 days for environmental testing after the Austin
American-Statesman reported that high
levels of arsenic and seven benzene-based compounds were found in the
pool and upstream on a hillside overlooking
Barton Creek. It was suggested that a possible source of the
contamination was wastes dumped from nearby coal gasification plants that produced fuel for city lighting from the
1870s to 1928. Subsequently, it was determined the contaminant
levels do not pose a threat and are from urbanization, not a waste
dump. Retired hydrologist Raymond M. Slade, Jr.,
who supervised and authored many scientific studies on Barton Springs
during his working career, prepared a detailed professional opinion on
the matter and you can read
it here. Mr. Slade concluded that although the water quality of
Barton Springs is still well within swimming criteria, it is likely
that uncontrolled urbanization in the watersheds feeding the Springs
will eventually cause Barton Springs to be degraded to the extent that
it must be permanently closed to swimming.
In 2006, the United States Geological Survey published a Scientific Investigations Report that summarized water quality sampling performed from 2003 to 2005. Barton Springs was found to be affected by persistent low concentrations of atrazine (an herbicide), chloroform (a by-product of drinking water disinfection), and tetrachloroethane (a solvent). Concentrations peaked 1-2 days after storm events, and Upper Spring was found to be more contaminated and influenced by a contributing flow path that is separate from those leading to the other springs under all but stormflow conditions. The geochemical response at the Springs after storm events led the authors to conclude that when there is flow in the recharge streams, water directly enters conduits and is transported straight to the Springs. When there is no flow in recharge streams, water drains from the surrounding limestone matrix into the conduits that feed the Springs. You can get the report from the USGS website or right here.
In 2008, the fight to preserve Barton Springs was the subject of The Unforseen, a documentary co-produced by Robert Redford, who learned to swim there as a child. The movie uses the struggle over development in the Barton Creek watershed to illustrate the many clashes between private property rights and resource protection that are occurring across the country. The film drew great reviews, but some developers said it went too far and portays them unfairly. Environmentalists said the movie is not hard enough on those who would develop lands at the expense of common resources like Barton Springs.
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Robert Redford at Barton Springs talking about environmental stewardship, from The Unforseen. You should go see it. |
For more info on
Barton Springs visit the Barton Springs/Edwards Aquifer Conservation District.
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A view into the natural limestone depths from which Main Spring emerges. |
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The upper dam is visible in this view of the upstream portion of the swimming pool. The dam diverts stormwater flows around the pool. |
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This section of Barton Creek just below the swimming pool is a favorite dog park. Notice the discharge of Main Spring from the center of the dam. |
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When this photo
was taken in the early 1990s, the lower dam was being rebuilt and all
the flow from Main Spring was being routed through this
gate, which is normally the bypass channel for Upper Spring and Barton Creek. So this represents the discharge of both Main Spring and Upper Spring. Below the inner tube, note the grasping hands of a
swimmer submerged and prone in the cool discharge. |
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Built by Andrew Zilker in the early 1900s and located on the
banks next to the main swimming hole pictured above. It used to be a swimming pool but is now reserved for salamanders and other native aquatic plants and animals. Photo taken around 1991. |
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A view of Eliza Spring taken in July of 2008. |
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Part of it says:
Clear and icy, these springs over the years have drawn Indians, pioneers, and tourists to this spot. The waters are brought from limestone strata to the surface by the Balcones Fault, which bisects central Texas. Average flow is 27,000,000 gallons per day. |
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