WaterNSW monitoring significant metro rain event

WaterNSW monitoring significant metro rain event

07 February 2020

WaterNSW is closely monitoring the impact of an ongoing rain event over Greater Sydney’s dam catchment, including run-off from firegrounds around Warragamba Dam.

Acting on advice from the Bureau of Meteorology (BoM), WaterNSW is anticipating inflows into all metropolitan dam storages, including Warragamba Dam, as a result of rain predictions for the next 72 hours. However the forecast remains quite variable.

The BoM is forecasting around 200mm of rain over the Warragamba catchment across the weekend, and likely higher over metropolitan and Shoalhaven catchments. Warragamba’s storage is currently at 42.8% of capacity, while the metropolitan network total is 41.7%.

The catchments have been dry from the prolonged drought. At least 75mm of rain is required in the catchment before significant run-off is generated and inflows eventuate.

The current BoM advice is that the rain will not be at a level to raise major concerns about dam water quality impacts on Warragamba dam storage. However some debris/ash is likely to be transported into the storage.

Monitoring continues by experienced water quality scientists using sophisticated, real-time technology pioneered by WaterNSW which can predict any change in the dam storage’s water quality. WaterNSW is also in close contact with Sydney Water and NSW Health.

WaterNSW has already deployed two silt curtains to intercept floating organic material that could pose a water quality risk to the storage and is assessing the effectiveness of additional ash and sediment control measures around the storage.

Warragamba also has the capacity to select water from varying storage depths and as such is currently releasing water from 30 metres below the surface as a precaution.

CEO David Harris said that while the full impact on dam levels will be clearer in coming days, WaterNSW is well-prepared for water quality issues at Warragamba.

“Managing water quality in our dam storages is what we as an organisation do and our water quality scientists are highly-regarded experts. Some debris/ash is likely to be transported into the storage, but we are well-placed to manage the risk,” Mr Harris said.

“Over the years our people have pioneered highly sophisticated models that predict what’s coming into the storage so we can respond operationally to that information.

“This includes elevated monitoring by our expert scientists using state-of-the art vertical profilers and other instrumentation; we can draw water from different depths in the storage.

“Furthermore, we can source water from of dam storages elsewhere in the supply network if required. In short, we have many levers available to manage water quality.”

Media Contact – Tony Webber 0428 613 478.


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