Barossa Reservoir, lake in Australia

The Barossa Reservoir is a large body of water located in South Australia, surrounded by open land and gentle hills. The water is held back by a curved dam wall that visitors can walk along, offering views of surrounding vegetation, tall trees, and open grassland.

The Barossa Reservoir was built between 1899 and 1902 to supply water to nearby towns and farms, especially in the Gawler area. The curved arch dam design was innovative for its time, showcasing engineering methods that enabled over 400 workers to create a reliable structure that attracted international attention.

The dam's parabola effect gave it the name "Whispering Wall": a voice spoken at one end of the 144-metre wall is heard at the other. The reservoir grounds, with thick scrub, tall red gums and pines, are used for picnics and bird-watching, and in 2008 Engineers Australia placed a marker recognising the wall's engineering heritage.

The dam wall stands at Williamstown in the northern Mount Lofty Ranges, reached from the Whispering Wall car park; the wall is 144 metres long and 38 metres high, with the reservoir covering 12.7 hectares below it. The vegetated surrounds are protected, and the site is used for picnics and bird-watching among red gums and pines.

The Whispering Wall is a remarkable acoustic feature of the curved dam wall where a person can whisper at one end and their voice carries clearly to the other side over 140 meters away. This quirk makes it a popular photo spot and an entertaining activity for visitors who want to test this unusual sound effect.