The dam levels in Sydney have finally fallen below the 40% level that is supposed to trigger the use of groundwater supplies. The groundwater that was discovered in the large empty spaces in Morris Iemma’s head was one of the factors that suddenly made Sydney drought-proof without having to risk marginal seats in the Sutherland Shire.Unfortunately the groundwater supplies are still being investigated and might not be ready for two years. So there is a real possibility that the dams will fall to 30% (the trigger level for the desalination plant) before a drop of water is delivered from the groundwater fields.

But the real miracle of the situation is how despite one of the worst droughts on record, the dams have only fallen 1% over the course of the year. The answer is massive transfers of water from the Shoalhaven. In any one week, up to 80% of Sydney’s weekly water supply comes from the Shoalhaven and has averaged 27% for the year.

It takes a lot of power to move this much water around. The Sydney Catchment Authority is no longer publishing its current electricity usage on its web site, but in between 2001 and 2004 (the period in which this pumping began) electricity usage for the SCA went up by 4500%. The additional usage, almost certainly coming primarily from Shoalhaven transfers, was the same amount of electricity that would be required to power a 125Ml/day desalination plant. The size of the transfers has greatly increased since 2004, so how many desalination plants worth of electricity are these transfers using now.

It seems ironic since the Iemma government is using all this electricity to artificially keep the dam levels above the trigger point at which a desalination plant will have to be built.

The graph below shows the extent of transfers for the year.