Barton Springs
68 º Fahrenheit, always
Pool map
History Geology Biology Maintenance
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The pool is fed by the Edwards Aquifer, a karst limestone system of caves deposited around 100 million years ago. Dinosaur tracks can be found in the pool's shallow end. Native Americans from the Lipan Apache, Comanche and Tonkawa tribes lived in the vicinity. The Tonkawa were a nomadic people who followed the great herds of migratory animals to hunt. Buffalo herds were a common sight at the springs.Spanish friars located three missions on the southeast side of the pool 1730-1731. Over a century later, in 1937, William "Uncle Billy" Barton patented the area that is now known as Zilker Park. He built a small cabin near the springs and named each of the three main springs after one of his daughters, Parthenia, Eliza and Zenobia.
- Parthenia -This is the main spring that flows into the pool between stands #1, #6 and #S1. It emerges from the fault crack in the wall under stand #6 and the bed of limestone under the ledge that runs from Shallow 1 to the diving board.
- Eliza -This is the spring that flows out of the pit behind the food stand. The pit around Eliza Springs was dug in 1917. The constant flow of 68 degree water from the spring keeps the air in the pit cooler than elsewhere. In the 1920s this pit served as the summer meeting place for members of the Elk's Lodge because it stayed cool--a place of welcome relief before electric service was widespread.
- Zenobia - This spring flows from above the shallow end of the current pool.
- Sunken Gardens is the site of a fourth spring along the creek. It flows from the ring of rocks that form a natural amphitheater on the south side of the creek, about 50 yards down from the damn at the deep end.
A.J. Zilker. a merchant, purchased the land 1905-13, and in 1918 and 1931 he deeded it to the people of Austin as a park.
The damn at the deep end and the decks on the south side decks date from 1923. The main building was erected in 1946 as a replacement for an older building (built in the late 1920s) that was damaged in the floods of 1935. The 1900 floods destroyed a bridge just upstream of the pool. This bridge's foundations can still be seen on the south side of the creek near the shallow end gravel trap. The deck on the north side and flood bypass system were built in 1974 to reduce the damage caused by floods and to reroute the creek out of the pool.
Some high-water marks:
- 1995 Memorial Day - Water rose to the top rail of diving board.
- 1991 December - Water covered stand #1.
- 1935 - Water crested 5 feet above the top deck.
Geology
The limestone formations that form the pool bottom and the aquifer were laid down in the lower Cretaceous period (66 million-144 million years ago). The Balcones Fault system has brought the Edwards Limestone (and its water) to the surface. This fault system has nearly a 1200 foot (approx.. 400 meters) displacement. Most of its movements occurred around 22 million years ago.The area has an interesting history with periods of erosion mixed with periods of being flooded under the sea. The retreats and advances of ice during the Ice Ages caused multi-layered, complex strata to be formed in the Central Texas area. The present day springs probably opened around 9000 years ago. The springs changed very little from then until the European colonists arrived and began engineering projects.
The Balcones fault can be seen under the lifeguard stand to the west (shallow end) of the diving board. The uplifted block of Edwards Limestone is found to the west of the fault, while to the east of the crack is a different type of rock, possibly Del Rio shale. The aquifer can be thought of as a giant sponge. The cracks and caves in the bed of limestone allow surface water to flow into the pool and down stream. This water is like an underground river. When it rains, the flow rate of the springs increase slowly. Typically, the springs will reflect a non-flood rainfall about 24 hours after the beginning of the rain. The increase in flow rate is usually accompanied by an increase in turbidity. After long periods of little or no rainfall, the spring's flow decreases and the clarity of the water increases. The average flow rate is 27,000,000 gallons a day. The flow rate for the month of May, 1996, was 14,212,000.
Biology
The waters of Barton Springs, 68 º Fahrenheit, year-round, are home to catfish, carp, bass, turtles, eel, crawfish, tetras, silverback/darters and the Barton Springs salamander (Eurycea Sosorum). The salamander is an endangered species found only in the three of the springs here. While most salamanders loose their external gills, the Barton Springs salamander is unusual in that it retains its gills. Most of these bottom dwellers are found in and around Parthenia and Eliza springs. The salamander population has been slowly increasing ever since the use of chlorine was discontinued in 1992. It is currently under for the endangered species list.It also attracts a great variety of birds. Commonly seen:
- belted kingfishers
- great blue herons
- mallards
- red-bellied woodpecker
- red-tailed hawks
- rock doves (pigeons)
- ring-billed gulls
- cormorants
- golden-fronted woodpeckers
- great-tailed grackles
- starlings
- northern cardinals
- blue jays
- cedar waxwings (winter)
- wood ducks
- yellow-crowned night herons
- sharp-shinned hawks
Plants growing in the pool include:
- Luwegigi (These ball shaped plants may have either red or green leaves.)
- Potamogeton (This plant has long spear-shaped leaves and grows underwater in long beds.)
- Pond weed (This plant forms the clumps on either side of the number two stand.)
- Algae (various types)
- Calothrix (This is what makes the shallow end of the pool so slippery.)
- Bratrachospermum (red colored algae)
- Caladophora (accounts for 10% of plant growth in the pool)
- Oscillatoria (blue-green algae found on the walls)
Maintenance
The water in the pool is lowered once or twice a week for cleaning. During cleaning, algae and silt are rubbed off the bottom of the pool in the shallow end with a rotary brush attached to a Bobcat front end loader. A drag brush is also attached to the Bobcat to remove silt off the gravel beach. All of the material that the Bobcat brushes off of the bottom is washed down and out of the pool with a fire hose. High pressure water sprayers called "blasters" are used to wash algae from the walls and places that the Bobcat can't reach.
Along with other maintenance chores, sweeping, scrubbing and painting tend to take up a good deal of staff time. The pool has two large changing areas with showers and four restrooms that need to be cleaned daily.
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