Warragamba to exceed capacity, spill likely within days

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

WaterNSW modelling based on Bureau forecasts indicates that Warragamba will spill, though the exact timing and volume will depend on catchment rainfall and the resulting inflow to the dam.

Based on Bureau’s most likely forecast of 35mm of catchment rain received in 48 hours, the dam could reach a peak spill rate of about 40 gigalitres per day (GL/day), well below the spill peak experienced in early April, which exceeded 200 GL/day.

A less likely rain forecast scenario of 60mm over the Warragamba catchment over a 48-hour period would result in a spill peak in the vicinity of 100 GL/day.

It is likely that a number of smaller Greater Sydney dams will continue to spill including Cataract, Nepean, Woronora, Tallowa, Greaves Creek, Medlow Bath, and Middle Cascades. Avon Dam (currently 93% of capacity) may also spill.

Background

Spills from Warragamba Dam are not uncommon, occurring more than 50 times since 1960.

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.

· Check the Bureau website to receive the latest weather and flood information – http://www.bom.gov.au/

· For emergency information, contact the NSW SES – 132 500 or https://www.ses.nsw.gov.au

Media contact – 02 9685 4350 or email media@waternsw.com.au