Warragamba Dam: Forecast rain could bring more headaches

Penrith City is forecast to receive much-needed rain over the next five days, but it may not be entirely good news for the water supply according to a professor of water engineering.

Rains forecast for Penrith City could have an adverse effect on the water quality at Warragamba Dam. Picture: Toby Zerna

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Penrith City is forecast to receive much-needed rain over the next five days, but it may not be great news for Sydney’s water.

Warragamba Dam provides a large proportion of the city’s drinking water, but recent bushfires in the dam’s catchment area has some experts worried.

The dam has been almost entirely surrounded by fire for the past few weeks and remains closed to the public due to fire danger.

Associate Professor of water engineering at UTS, James Ball, said there was a risk that the dam’s water could become contaminated with ash and other unwanted substances.

“There’s a number of potential implications from the bushfires,” he said.

“One is the increased pollution, but the other is some of the soil around the dam will turn hydrophobic and increase the potential of water quality issues.

“A lot of the humic substances undergo decay in the catchment area, and if they’re transported, you can have a major issue with the quality of the water being collected in the dam.”

Associate Professor of water engineering at UTS, James Ball, doesn’t believe the rains will have any significant impact on Warragamba Dam’s water level. Picture: Tim Hunter.

However, Associate Professor Ball said people shouldn’t notice a change in the water running from their taps.

“Most of the water going into the Sydney drinking water system is treated, so it goes through a major process at the Prospect Treatment plant,” he said.

“My expectation is there wouldn’t be a major impact, and I wouldn’t expect the drinking water to be unusable.”

Associate Professor Ball said the forecast rains wouldn’t have any substantial impact on the dam levels, which sit at 43.6 per cent according to NSW Water.

“I’d be very surprised if any rains over the next month did anything for the water supply volume, which will remain a problem,” he said.

“These rains will be positive for a variety of reasons. They will create a new set of problems to be dealt with, but the benefits outweigh the negatives.”