02-07-2025
SA Water to face penalty over botched reservoir drainage incident
SA Water is facing a criminal penalty for causing "serious environmental harm" when an engineer ignored a water quality test result while draining a Barossa Valley reservoir for maintenance work, a court has heard.
The water utility — which is wholly owned by the SA government — appeared in the Environment Resources and Development Court over its actions when draining the Warren Reservoir, about 10 kilometres from Williamstown, in May 2023.
The court heard that a test result indicating poor water quality during the draining procedure was "not given much credibility" and "ignored", allowing the escape of grey clay silt and "a significant smothering event for the downstream habitat" of the South Para River.
A lawyer for SA Water told the court the maintenance work was scheduled to replace the reservoir's original valves, which had been installed when it was built more than a century ago during World War One.
Dr Victoria Gilliland, for SA Water, said the maintenance works were "necessary" to replace the aging and unreliable valves, because only the middle of its three intake valves was "safe to operate".
She said the "very thing" the maintenance works were trying to prevent was what happened, when the bottom could not be immediately closed to prevent further damage to the surrounding waterways.
She said there was a known difficulty with closing the bottom valve, but there was no immediate attempt to close it when the poor water quality test was reported.
"Ultimately there is no dispute that what happened is that that reading was ignored and no action was taken in relation to that reading," Dr Gilliland said.
She told the court SA Water admitted "mistakes were made" but had immediately reported the event and spent almost $1 million on remedial works — including ongoing testing.
Dr Gilliland said the corporation had immediately pleaded guilty and urged the court to impose a fine "at the lower end of the scale".
The court heard SA Water had two prior convictions for environmental breaches, in 2004 and 2009, but that procedures had improved since.
Stephanie Wilson, prosecuting, said samples taken after the incident found recently deposited grey clay silt almost 30 centimetres deep in areas closer to the reservoir.
She said the slurry was also detected almost 3 kilometres into the South Para River.
Ms Wilson told the court SA Water had a lack of contingency planning which may have prevented the environmental harm, and should have acknowledged the initial poor quality water reading.
She said the engineer overseeing the project had explained that "she wasn't sure whether the samples were being taken accurately due to it being a shallow site and that she planned to retest … the following day".
But, Ms Wilson said by the following day, the reservoir had drained completely.
She said SA Water also knew that once opened, the bottom of three valves at the reservoir could not be immediately closed, and that efforts to prevent the harm were delayed, in part due to wet weather and the terrain, with a bung not installed for several days.
"While it is obvious there were logistical and technical issues hampering those efforts to take action sooner, better understanding of the risk and preparation that took into account the difficult terrain … might have improved the response," Ms Wilson said.
She said SA Water were "wholly unprepared for what occurred".
Senior Judge Michael Durrant will impose a sentence on a date to be set.
