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Sydney’s water supply at ‘serious risk’ of contamination as bushfires bear down on Warragamba Dam


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Ash from raging bushfires could contaminate Sydney’s drinking water with blazes closing in on a dam that holds 80 per cent of the city’s supply. 

Two giant fires are burning on the north western edge of Lake Burragorang, west of Campbelltown, where the Warragamba Dam is located. 

The massive blazes are expected to combine and the Rural Fire Services fear they could spread across the lake to the east. 

University of NSW professor Stuart Khan, who has studied the threat of bushfires to water supplies, told Daily Mail Australia that this event would pose ‘some serious water quality risks’. 

He said if the fires are followed by a large rain fall event, the sediment from the ground will wash into Warragamba Dam. 

Smoke erupting above Green Wattle Creek where Rural Fire Services are battling an out-of-control blaze threatening to contaminate Sydney’s water

The ash, which is comprised of organic carbon and phosphorous, can cause chemical reactions to occur in the water which can produce toxins. 

‘These can lead to serious water quality impacts including deoxygenation and the growth of cyanobacteria and algae,’ professor Khan said.  

‘These organisms can produce toxic chemicals or change the taste and odour of water. 

Deoxygenation can also make other chemicals more soluble in water, such as iron and manganese- which can turn water orange or red. 

Warragamba Dam (pictured) is at risk of contamination from bushfire ash which could cause discolouration and taste changes which could last months

Warragamba Dam (pictured) is at risk of contamination from bushfire ash which could cause discolouration and taste changes which could last months

He said given summer rainfall levels the risk of an algae-bloom was high. 

Based on previous incidents, he said, if infected, the altered water conditions and off-taste could last months. 

Their is currently no fire risk to the treatment plant and its major infrastructure.

A WaterNSW spokesman said while water quality is yet to be compromised, they are confident they would be able manage the risk to public health.

 ‘Fires burning in Sydney’s catchment do not pose a risk to water quality in WaterNSW dam storages at this time,’ he said.

A fire (pictured) in the Blue Mountains near Katoomba was downgraded from a watch and act alert level to an advice alert on Monday night

A fire (pictured) in the Blue Mountains near Katoomba was downgraded from a watch and act alert level to an advice alert on Monday night

‘WaterNSW is liaising with Rural Fire Service and National Parks’ fire-fighting personnel working to manage the blazes. 

‘The potential for water quality impacts will depend on the extent and intensity of the fires and timing of the next significant rainfall.

‘Experienced water quality scientists use highly sophisticated, real-time monitoring technology and models to predict where in the storage water quality may change.

‘This combined with the capability to select water from various dams and from varying storage depths, ensures that optimal quality water is supplied to Sydney Water and local councils for treatment into safe drinking water.  

The Rural Fire service are currently fighting 125 fires across the state with 60 still to be contained.  

The fires have burnt through 1.6million hectares across the state. 

On Monday afternoon, hazardous wafts of smoke were once again swept across the city- blanketing western suburbs, such as Oakdale and Earlwood. 

Senior RFS spokesman Ben Shepherd said crews had been working to contain the Green Wattle Creek and Kowmunger Creek fires near the catchment and wind strength on Tuesday had reduced. 

‘The concern is that they will spot across the lake potentially putting at risks residential areas such as Oakdale and Silverdale and down to Thirlmere,’ he said.

 ‘Those fires still continue to spread and it’s expected to continue over the coming days.

Sydney has been engulfed by thick smoke as bushfires ravage the east coast, prompting health warnings for residents

Sydney has been engulfed by thick smoke as bushfires ravage the east coast, prompting health warnings for residents

‘We need people to understand that without significant rain, these fires are potentially burn for weeks and with more hot and windy weather on the way it is likely we will see more properties threatened.’      

In January, up to one million fish were killed when an algal bloom hit the Murray Darling Basin. 

In 2007, unusually hot weather followed by rain fall caused a 26km-long blue green algae bloom in Sydney’s water catchment.

The growth strained the processes of the treatment plan for months and changed the taste and odour of drinkable water. 

Commuter ferries sail past the Sydney Harbour Bridge as smoke haze from bushfires in New South Wales blankets the CBD in Sydney on Monday

Commuter ferries sail past the Sydney Harbour Bridge as smoke haze from bushfires in New South Wales blankets the CBD in Sydney on Monday

Read more at DailyMail.co.uk


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