The Harvey Water Irrigation Area (HWIA) is located to the west of the Darling Scarp on the Swan Coastal Plain, around100 kms south of Perth. It covers an area of 112,000 hectares (around 75 kms long and 15 kms wide) in three Irrigation Zones: Harvey, Waroona and Collie. There is currently around 10,000 ha of land under permanent irrigation for dairy farming, beef grazing and horticulture, with a total irrigable area of approx 30,000 ha. .
The HWIA is different from most Australian irrigation areas because it does not have a longitudinal river system from which water is diverted or pumped. Water has historically been supplied by gravity flow from dam to farm along a network of open concrete lined and earthen channels. These channels are being replaced as part of a major capital works program by Harvey Water with more efficient pipe distribution, still utilising energy-conserving gravity flow techniques.