Barton Springs Pool

Barton Springs is the fourth-largest spring system in Texas. Water from the Edwards Aquifer rises here through cavernous limestone in the Balcones fault zone, and from 1895 to 1978 it averaged nearly 370 gallons a second. For thousands of years the springs were a gathering place for Native peoples, Spanish explorers noted in 1714 that wild horses were plentiful, and the springs took the name of William Barton, an early settler. Saw, flour and grist mills and ice machines later ran on their flow.

The pool sits in the channel of Barton Creek inside Zilker Park. Andrew Jackson Zilker, the last private owner, deeded the land to Austin in 1918, and in the 1920s the city dammed the springs and built walks to make a larger swimming area. Today it covers three acres, runs from 0 to 18 feet deep and stays at about 68 to 70 degrees, so people swim year round. Dan Driscoll and Delmar Groos designed the Streamline Moderne bathhouse in 1947, and Robert Redford learned to swim here at five.

The springs are also habitat. The Barton Springs salamander, a federally listed endangered species, lives only in the pool and a few nearby springs, and the pool closes for cleaning on Thursday mornings partly to protect it. From the 1980s, runoff from subdivisions over the recharge zone fouled the water after heavy rains, and the fight to protect it produced the Save Our Springs Alliance and, in 1992, a campaign for stricter water rules. The Splash! exhibit beside the bathhouse explains the aquifer and its animals.