Warragamba Dam chance of small spill in coming days

The Warragamba Dam storage level is currently at 97.7% of capacity with inflows to the dam slowing as the rain clears.

The storage level is continuing to slowly rise with inflows from across the 9,000 square kilometre catchment area upstream of Warragamba Dam. However, the volume of these inflows is now slowly receding.

Most other smaller Greater Sydney dams are currently spilling, including Woronora, Nepean, Cataract, Avon and Tallowa.

The community should continue to monitor advice on river levels and any flood warnings from the Bureau of Meteorology.

• For the latest weather and flood information, check the Bureau website – bom.gov.au/
• For emergency information, contact the NSW SES – 132 500 or ses.nsw.gov.au

Background

Spills from Warragamba Dam are not uncommon, occurring more than 50 times since 1960. In 2024 the dam has spilled on 5 April (peak spill rate 220GL/day), 6 May (peak spill rate 30GL/day), and 7 June (peak spill rate 240GL/day),

The Warragamba Dam catchment area covers 9000 sq/km and stretches across much of the Blue Mountains to Goulburn in the south, and to Lithgow in the north.

As manager of the state’s major supply dams, WaterNSW operates Warragamba Dam in line with NSW Government operating rules and regulations.

These rules do not permit water being released to reduce the storage level ahead of predicted rainfall for flood mitigation purposes. This reflects the dam’s critical role in supplying 80% of Sydney’s drinking water.

Background – dam operations

During times of flood, the gates on Warragamba Dam automatically open and close based on water levels.

After rainfall has occurred and when the water rises above full supply level, the gates progressively open in sequence. As water levels begin to drop, the gates will progressively close in reverse sequence.