FEDERAL Water Minister Penny Wong has repackaged and relaunched CSIRO's Murray Darling Basin Sustainable Yield Reports.

The last of the 18 reports, analysing the impacts of climate change on surface and groundwater in the basin, was released in July.

However Senator Wong today launched a summary report, which reiterated CSIRO's previous findings that the environment would bear the brunt of the impacts of climate change.

CSIRO found median surface water availability to irrigators would decline by 4 per cent by 2030, under current water sharing arrangements, as the basin's large dams captured a greater proportion of surface water.

However flows at the Murray mouth would decline by 24 to 30 per cent.

The reports also found:

  • total flow at the Murray mouth has been reduced by 61 per cent and the river now ceases to flow through the mouth 40 per cent of the time, compared with 1 per cent in the absence of water resource development.

  • the median decline for the entire basin is projected to be 11 per cent by 2030, 9 per cent in the north and 13 per cent in the south.

  • current groundwater use is unsustainable in seven of the 20 high-use groundwater areas in the Basin and will lead to major drawdowns in groundwater levels in the absence of management intervention.

  • the expansion of commercial forestry plantations and farm dams will have a very minor impact on the total runoff reaching rivers across the Basin. However the impacts of farm dams is far greater in the Avoca, Campaspe and Loddon catchments.

CSIRO's analysis uses 15 global computer models, each created by different groups of climate scientists.

The CSIRO team has plugged three possible climate change scenarios - high, medium and low global warming - into the 15 computer models to produce 45 possible scenarios on what each catchment's rainfall and run-off will look like in 2030.

CSIRO has then ranked the scenarios from one extreme to the other and selected the mid-ranked (23rd) number as its best estimate.

Senator Wong highlighted the worst case scenario, predicted by one of the most extreme computer models, which found diversions in the "driest" years would fall by around 40-50 per cent in New South Wales regions, over 70 per cent in the Murray, and 80-90 per cent in major Victorian regions.

Senator Wong said the final report was a critical resource in the Rudd Government's work to restore the balance in the Murray-Darling Basin.