Sydney's largest dam set to spill

Warragamba's drum and radial gates open in 1973 (Panoramio)

A slowly moving trough, which is expected to take as much as three days to clear New South Wales, will dump enough rainfall into the catchments to ensure that Warragamba Dam, Sydney will spill for the first time in 14 years.

The floodgates of Sydney’s Warragamba dam are being tested as heavy rains put it on the verge of filling up for the first time in 14 years.

As the State Emergency Service keeps an eye on overflowing rivers, the Sydney Catchment Authority is expecting Warragamba to reach full capacity for the first time since August 1998.

Floodgates are scheduled to be tested for two hours from 8am (AEDT), with staff anticipating dam levels at one metre below full storage.

Sydney Catchment Authority acting chief executive Sarah Dinning says preparations are being made to release excess water.

‘Due to the variable weather conditions, we have staff available around the clock and the test will occur as soon as the dam reaches one metre below full storage,’ she said.

‘Once Warragamba Dam is 80mm above its full storage level the drum gate opens automatically.’

Evacuations are underway in one town and emergency crews are standing by in others as large parts of NSW continue to be deluged with the heaviest rains in more than 80 years. (source)

Perhaps it’s time to visit one of the dire predictions of Tim Flannery, Climate Commissioner (salary $180,000 for 3 days work), from 2007:

“Even the rain that falls isn’t actually going to fill our dams and river systems. In Adelaide, Sydney and Brisbane, water supplies are so low they need desalinated water urgently, possibly in as little as 18 months.”


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