Warragamba Dam levels have exceeded 80 per cent for the first time in nearly 10 years.
The dam, 60 kilometres west of Sydney, is the city’s primary water source. Its catchment stretches more than 9000 kilometres between Lithgow and Cooma.
The last time the dam’s levels rose above 80 per cent was June 2002, according to the Sydney Catchment Authority.
It was at its lowest in February 2007 when it fell to less than 33 per cent.
In April 2005, when the dam was at little more than 40 per cent of its capacity, the environmentalist Tim Flannery said it might be in terminal decline. It had only two years’ supply.
From January 2010 to 2011, dam levels increased from nearly 50 per cent to 76 per cent, as an unusually wet spring replenished supplies after the drought.
The last time Sydney dams were full was 1998.
Debbie Low, a spokeswoman for the Sydney Catchment Authority, says dam levels are typically affected by factors such as consistency of rainfall, soil moisture and evaporation caused by summer heat.
But they are also affected by political decisions and have political consequences.
Water had previously been transferred to Warragamba from the full Tallowa dam on the upper Shoalhaven River.
But the previous state Labor government cut off these transfers in 2008 and imposed a three-year moratorium. Excess water from Tallowa was instead diverted to surrounding rivers, which flowed into the sea. Transfers were resumed briefly in September but have since been cut off.
Had the transfers continued over this period, Warragamba would be close to full, according to projections obtained by the Herald.
The Greens say the government has manipulated Warragamba levels to keep them lower so the privatisation of the desalination plant at Kurnell is more attractive.
Now that Warragamba’s levels are more than 80 per cent, the supply from the desalination plant has been reduced.
If Warragamba levels stay above 80 per cent for two years, the plant’s supply will be cut off until levels reach 75 per cent again.
The government is trying to sell the Kurnell plant for an estimated $1.5 billion.
The Greens oppose the sale, arguing that the plant should be shut because its output is unnecessary and adds nearly $100 to the average water bill.
They point to Warragamba’s rise above 80 per cent as further evidence it is not needed.
But the government has welcomed the rise of dam levels and says it will not affect the decision to privatise the desalination plant.
“This will have absolutely no impact on the long-term lease of the plant,” says the Minister for Finance and Services, Greg Pearce.
