The Yarragadee Aquifer is a significant freshwater aquifer located in the south west of Western Australia and predominantly beneath the Swan Coastal Plain west of the Darling Scarp.
The aquifer is quite deep, situated hundreds of metres below ground level and with a thickness ranging up to about two kilometres.
Formed during the Jurassic Period, the Yarragadee Formation is composed primarily of non-marine fluviatile feldspathic, poorly sorted sandstones which are porous and poorly cemented, hence allowing for considerable groundwater reserves.
It grades from a shale-siltstone dominated base to a cleaner sandstone in the upper portions of the formation, probably representing increased subsidence or filling of the basin during the late Jurassic.
The Dalkeith Hot Pool was formed by water from the Yarragadee Aquifer.