The Department of Water is responsible for the management of water and issues water allocation licences to the South West region's three public water utilities, Water Corporation, Aqwest (Bunbury Water Board) and the Busselton Water Board.
Licences are also issued to private water users such as large horticultural enterprises requiring groundwater from confined aquifers. Irrigation is a major water user in the South West.
Water comes from a variety of sources including aquifers and dams.
With the exception of Bunbury and Busselton, drinking water schemes in the State's South West are operated by the Water Corporation.
A number of South West communities receive their drinking water primarily from surface water sources including Pemberton, Manjimup, Bridgetown, Boyup Brook, Kirup, Balingup and Margaret River.
On the coastal plain, most towns are supplied with groundwater from the Yarragadee or Leederville Aquifers. These include Bunbury, Eaton, Australind, Capel, Busselton and Dunsborough.
The Harris Dam, 12 kilometres north of Collie, supplies water to Collie and 31 towns connected to the Great Southern Towns Water Supply Scheme. The Water Corporation can also transfer water from Harris Dam to the State's Integrated Water Supply Scheme via the Stirling Dam if required.
The Water Corporation supplies bulk water to Harvey Water (formerly South West Irrigation Cooperative) from dams in the Darling Scarp, Waroona, Samson, Logue Brook, Stirling, Harvey and Wellington. The Glen Mervyn Dam near Donnybrook supplies the Preston Valley Irrigation Cooperative.
Stirling Dam near Harvey, forms part of an integrated water supply system servicing the South West, Perth Metropolitan and Goldfields-Esperance regions. Officially opened in November 2002, it supplies up to 10 per cent of the Integrated Scheme's water requirements.
In January 2013, the first seawater flowed into the second stage of the Southern Seawater Desalination Plant, near Binningup, marking a major milestone in the $450million expansion to double the capacity of the plant to 100 billion litres of drinking water a year. Water from the plant is treated and delivered to the Integrated Water Supply Scheme as drinking water. The first stage of the plant was completed in 2011.
In June 2010, the State Government announced the Collie River Salinity Recovery Project. The project will aim to improve salinity levels in the 186GL capacity Wellington Dam by diverting and treating saline river flows from the east branch of the Collie River, opening up the resource to support proposed industry expansion and development in the region.