Three acres in size, Barton Springs Pool is fed from under ground springs and is on average 68 degrees year round. Barton Springs Pool has been a popular swimming hole for decades, but even more people showed up once it became part of a city park in 1917. In 1929, workers enlarged the irregular-shaped pool to 1,000 feet long by building a concrete lower dam and sidewalks on both banks. In 1932, the city added an upper dam. Over the years the springs has been the site of a flour mill, a source of drinking water for many citizens and a popular location for baptisms, family picnics, social gatherings, musical performances, fishing and swimming.