: News Article

Odds on for water to top spillway

19/01/2004

It’s odds on for the wet season to deliver one of the north’s most spectacular events. The bet is that water will top the Ross River Dam spillway in February.

That’s comes from Ian Hamilton, who has three decades experience with water supply in Townsville and Thuringowa.

Mr Hamilton is the first and only Chairman of NQ Water and he says it’s not only instinct that tells him there’ll be more good rain.

“Our calculations indicate that we need around 34 mm runoff over the whole catchment to fill the dam to the new reduced spillway height,” he says. “That’s equal to falls of around 100 mm when you take into account losses.”

“The median rainfall for the December to February quarter is around 400 mm. That’s enough rain to push a flow over the lowered spillway and give us twelve months supply in the dam.”

January rain has doubled the volume in Ross River Dam to almost 64 per cent of capacity, taking into account the reduced height of the spillway.

That’s runoff equal to more than 24,000 Olympic sized swimming pools into Townsville and Thuringowa’s largest and most important water storage.

The spillway was lowered 3.6 metres late last year in line with recommendations from an expert panel advising on an extensive upgrade to the dam. Capacity is expected to be reinstated before the 2005 wet season with the installation of gates.

The State Government has agreed to fund two-thirds of the upgrade which is expected to cost between $60 million and $90 million.

At around 11,500 ML, Paluma Dam is around five per cent the size of Ross River Dam at full capacity.

Mr Hamilton says nevertheless, the Mt Spec system is an important supply to Townsville and Thuringowa, providing about 20 per cent of demand annually.

Paluma Dam is at just over 27 per cent capacity.

© 2004 NQ Water