Pre-emptive dam release 'pointless'
The Queensland government shelved plans to reduce the Wivenhoe Dam level late last year because such reductions would be “pointless” in avoiding major floods, according to the then-water minister.
Former natural resources minister Stephen Robertson was the first witness to be grilled by the $15 million floods commission of inquiry, which is focusing on dam management over the next five days.
Mr Robertson today bristled at suggestions he dragged the chain in pursuing state agencies over the possibility of reducing the “full supply level” of Wivenhoe Dam to reduce flood risks amid warnings of a larger than normal wet season.
Former natural resources minister Stephen Robertson leaves the inquiry hearing for lunch today. Photo: Daniel Hurst
Wivenhoe Dam can hold a total of 2.6 million megalitres but is deemed to be “full” of drinking water when it reaches 1.15 million megalitres, with the remaining space used as a flood mitigation buffer.
The inquiry heard Mr Robertson wrote to the South-East Queensland Water Grid Manager on October 25 seeking advice on whether the normal dam storage maximum could be lowered temporarily to increase the space available for flood mitigation.
Despite asking for the response by the end of November, the formal response from SEQ Water Grid Manager Gary Humphrys did not arrive until Christmas Eve.
Water flows out of Wivenhoe Dam during January's flood. Photo: Dean Saffron
That response said water agencies did not have any objection to reducing the dam’s full supply level to 95 per cent, down from its normal 100 per drinking water maximum.
Mr Robertson told the inquiry he had in fact received an informal briefing from the Water Grid Manager to this effect on December 13.
But he said he came to the view that a 5 per cent reduction to the Wivenhoe Dam full supply level would have been “pointless” in safeguarding against large flood events given the large amount of rainfall that was already occurring at that time.
Flood peaks in Brisbane
The flooded Brisbane River spills into residential areas close to the CBD. Photo: REUTERS/Tim Wimborne
“I would have discussed that letter with the director-general. My view was that a 5 per cent reduction was meaningless in the context of what was occurring and there would be no point in continuing to pursue that,” Mr Robertson said.
Mr Robertson rejected suggestions he had taken too long to chase up the formal response from the Water Grid Manager and subsequently take action.
“It is clear under the relevant act that as minister I can act in the public interest when there is demonstrable reason for me to do so. I did not consider that demonstrable condition had been reached. I was satisfied that my request was being responded to, promptly.”
Asked whether the project to reduce the full supply level was abandoned, Mr Robertson said he would use the word “parked”.
Documents submitted to the flood inquiry show Mr Robertson sought “urgent advice” from the South-East Queensland Water Grid Manager on whether dam levels should be dropped, amid warnings of a bigger than normal wet season.
Mr Humphrys told Mr Robertson that dam operator Seqwater had no objection to drawing down Wivenhoe and Somerset dams down to 95 per cent of their full supply level.
“Based on information currently available Seqwater has advised that releasing water to below full supply level may provide some benefits in terms of reduced community and operational impacts during minor inflow events, such as has occurred over the past month,” Mr Humphrys said in the December 24 letter.
Mr Humphrys said the reduction would be aimed at preventing minor flooding events, but would have a “negligible” effect on preventing impacts from major downpours.
“The Water Grid Manager has advised Seqwater that, from a water security perspective, it would not object to water being released from Wivenhoe and Somerset dams to 95 per cent of storage capacity at any time until end March 2010,” he wrote.
“Under this recommendation, storage levels could potentially be reduced by up to about 77,250 [megalitres]. This is equivalent to the amount of water released between 13 and 16 December 2010, through a single gate.”
However, the government did not announce a reduction in the full supply level in the following weeks. The Brisbane River flood level peaked on January 13, inundating thousands of homes and businesses.
The government announced in February it would reduce Wivenhoe Dam to 75 per cent of its normal drinking water capacity until the wet season ended, but said such a move would not have been effective in preventing the massive January floods.
The inquiry’s public hearings began today in Court 17 at the Brisbane Magistrates Court, which was packed with lawyers and spectators in the public gallery,
The inquiry, headed by Court of Appeal Justice Catherine Holmes, is focusing on dam management during the first five days of hearings.
Earlier, counsel assisting the inquiry, Peter Callaghan, said the inquiry had received hundreds of gigabytes of information, equivalent to six million printed pages.
“That is, by any standard, an enormous amount of information,” he said.
The inquiry is set to examine a range of issues stemming from the summer's deadly and devastating floods, including whether Wivenhoe Dam water releases into the Brisbane River were mismanaged.
Mr Robertson is among 13 witnesses expected to be called to give evidence in the first week.
Others include Bureau of Meteorology Queensland regional director Jim Davidson.