Wettest spring in 20 years tops up SA reservoirs

South Australia’s reservoirs have enjoyed the wettest spring in 20 years, with the storages capturing more than 80 billion litres of water during the unseasonably winter-like months.

Inflows to the state’s reservoirs during spring surpassed what was received in winter by around 30 per cent, with this year’s feat only the second time that’s happened since 2002.

Natural inflows from spring rainfall lifted total storage levels to 93 per cent at the beginning of December – the highest start to summer in recorded years – compared to only 72 per cent on the same day last year.

SA Water’s Senior Manager of Wastewater Expertise and Environment James Crocker said the sustained spring rainfall prompted five reservoirs to safely release water during this time, as the storages reached full capacity.

“We have to go back to 2016 – which remains the wettest combined winter and spring over the past 20 years – for the last time five of our reservoirs released water,” James said.

“A late rainfall rally in August set up prime soil conditions for spring to generate a significant impact on water levels in our reservoirs, growing in leaps and bounds particularly during September, which delivered the year’s largest individual day for inflows to date – seven billion litres during the 24 hours on 18 September.

“Reservoirs such as Kangaroo Creek and South Para enjoyed rapid increases in their storage levels, leading to natural water releases from their spillways in October and November, respectively.

“Excitingly, we witnessed Kangaroo Creek’s new 50-metre-wide spillway in action for the first time since our major dam safety upgrade, as it safely channelled water out of the reservoir downstream into the River Torrens.

“Unlike these reservoirs, our Mount Bold and Myponga storages have a series of gates atop their dams that are controlled manually to release water and manage water levels in the reservoir.

“We performed several controlled releases from our two gated dams during spring, with the aim of managing inflows from the catchment area by moving water out of the reservoir when we have the capacity to do so, while minimising the impact downstream.

“Once again trumping recent years, inflows from winter and spring combined led to the highest total increase in our reservoir levels, with them now sitting at a healthy position as we move into the warmer months.”

SA Water’s metropolitan reservoirs are currently sitting at a total capacity of 91 per cent, storing a combined 181 billion litres of water.

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