Heavy rainfall across the Sydney catchment area has resulted in dam storages receiving the best inflows in nearly three years.
Warragamba Dam received inflows of 40GL per day and, based on Bureau of Meteorology (BoM) forecasts, WaterNSW predicted its capacity to rise above 50 per cent for the first time since August 2019.
The Warragamba storage level reached 69 per cent on 11 February, the dam storage’s best inflows since April 2017, recouping nine months of water supply in less than a week.
Across other metropolitan storages the total volume rose from 43 per cent capacity on 7 February to 71.1 per cent on 11 February.
As of 11 February, the Nepean dam is at 100 per cent capacity, and all metropolitan dam storages have had significant inflow. Cataract is at 70.2 per cent, Cordeaux is at 70.1 per cent, Avon is at 82.4 per cent and Woronora is at 60.8 per cent capacity.
The Shoalhaven River received 114mm on 8 and 9 February, generating inflows into Tallowa Dam at a rate of 12GL per day.
While it is likely some ash and debris has been washed into the upper reaches of the Warragamba system, there is no impact on the water quality being supplied for treatment. Any surface debris is avoided by extracting water from 30m below the surface as a precaution.
Monitoring continues by experienced water quality scientists using sophisticated, real-time technology pioneered by WaterNSW which predicts any change in storage water quality.
WaterNSW has already deployed two silt curtains to intercept floating 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 30m below the surface as a precaution.