Minister for Climate Change and Water, Senator Penny Wong, yesterday launched the South West Sustainable Yields project, part of a $5.19 million national program led by the CSIRO to assess the future impacts of climate change and other factors on water supply.

"Stream flow in the south-west has declined by over 50pc since 1976, so it is clear that we are already seeing changes in the climate in this part of Australia," Sen Wong said.

"This project will provide crucial information on current and future water yield, taking into account climate change and other factors, such as changes in agricultural production."

The study is one of three new sustainable yields projects being undertaken by CSIRO to build on the Murray-Darling Basin Sustainable Yields project, which is due for completion shortly.

The South West Sustainable Yields (SWSY) project will cover 39,043 square kilometres of surface water catchment and 37,186 square kilometres of groundwater management areas from Geraldton to Albany.

The study is set for completion in December 2009.

Along with the south-west study, work has commenced on the Tasmanian Sustainable Yields project and the Northern Australia Sustainable Yields project.

Once completed, these scientific assessments of water yield in Australia's major water systems will allow future decisions about water use, planning and management to be based on the best available scientific data.

* More information about the SWSY project can be found at: http://www.csiro.au/partnerships/ SYP.html