Several dams are overflowing across the states as rainfall and extreme weather conditions continue from two collided systems.
The volume of water spilling from Warragamba Dam in NSW is currently 300 gigalitres per day (GL/day), after falling from an overnight peak of 500GL/day.
This is down from yesterday’s initial spill rate of 450GL/day yesterday (Sunday, 21 March) as days of heavy rain across the catchment continue to generate large inflows into the dam.
With more rain forecast by the Bureau of Meteorology in coming days, the likelihood is that the spill rate could rise to a second peak, possibly midweek.
Other Sydney supply dams are also receiving inflows, with Nepean, Cataract, Cordeaux and Avon dams all spilling.
On current forecasts it is likely Warragamba will spill for at least another week and thereafter lower volume inflows into the dam storage could continue for some time.
Modelling indicates that approximately 1500GL of water will flow into the dam in the seven days since the extreme weather event commenced, a figure that represents 75 per cent of the dam’s storage capacity of 2000GL.
WaterNSW is maintaining a dedicated 24-hour incident management team that is working closely with the Bureau and the NSW State Emergency Service to monitor weather and dam inflows.
WaterNSW will continue to work closely with Sydney Water and NSW Health throughout the rain event, to watch for potential water quality impacts on untreated supply.
Rainfall a positive sign for Canberra’s dams
Canberra’s dams have reached a milestone 100 per cent total storage capacity on 22 March for only the second time since completion of the enlargement of the Cotter Dam in 2013.
Following extreme temperatures in early 2020, and two of Australia’s driest years on record, water storage levels across the ACT dropped below 45 per cent (123.6GL) in February 2020.
A wetter than average 2020 and the commencement of a La Nina event has meant that storages have recovered significantly with all four of the ACT’s dams now full and holding 277.83GL.
Icon Water Managing Director, Ray Hezkial, said, “We’ve been pleased to see a considerable increase in rainfall over the last twelve months, compared to recent years, and this has meant Canberra’s water storages are in a much healthier place than this time last year.
“While the current rainfall has filled up storage levels, Icon Water are always planning for future droughts and are considering all options to protect Canberra’s long-term water security.
“While it may not seem the case at present, Australia is the second driest continent on Earth, and we cannot rule out significant drought again in our future,” Mr Hezkiel said.
“We’re considering a number of viable options to ensure Canberrans have a secure water supply for now and the future and of course, we’ll be engaging with the community to hear their thoughts in this space as well.”
Queenslanders urged to stay safe
Queenslanders are being urged to stay safe during the current extreme weather conditions affecting the state.
There has been very intense rainfall activity affecting various parts of the state in the 24 hours to 22 March, particularly the south-east region of Queensland.
Emergency Services crews have been called to numerous incidents, including a number where people have been caught in floodwaters in their vehicles.
Minister for Fire and Emergency Services, Mark Ryan, urged people to heed the warnings from agencies including the Bureau of Meteorology.
“We are in a situation at the moment where very heavy downfalls of rain are occurring in very short periods of time, which is leading to dangerous situations arising very suddenly,” Mr Ryan said.
“It is imperative that people stay abreast of the weather warnings and also that everyone take a very cautious approach when driving on the roads.
“Severe storms are dumping heavy falls, leading to flash flooding.
“We all have a responsibility to make good decisions on the road to keep other drivers and ourselves safe.
“But that is especially the case during extreme weather events.
“If it’s flooded forget it.”