Sunken Gardens
Old Mill Spring, also known as Sunken Gardens Spring or Zenobia Spring, is located on the south side of Barton Springs Pool. Like Eliza Spring, the early 20th century structure built around the spring is now closed to public access due to safety and endangered species habitat issues. Scientific analysis show that the water at Old Mill Spring has a slightly different chemistry than that of Main Barton Spring and Eliza Spring, even though it is less than half a mile (800 m) away from these springs.