Since its construction in 1903, the weir regularly overflowed, prompting a wall‑raising project completed in 1951. Overflows continued through the 1950s and 1960s, but the previous one before 1996 occurred in 1974, after rainfall began to decline in the mid‑1970s.

Fast forward to September 2026: the reservoir is only 42 % full and winter rainfall is at a historic low. Over the past ten years an average of 75 billion litres of streamflow entered Perth’s dams each year, yet this year just about 12 billion litres have been collected – a sharp drop from the long‑term average of 420 billion litres.

Waterwise programs manager Damien Postma explains that, under today’s climate, it would take a cyclone to push the dam to overflowing, and even then the water authority would likely stop the spill to protect the scarce supply.

The contrast between the abundant rains of the 1990s and the severe drought of today highlights how dramatically Perth’s water security has changed, making everyday conservation measures – like shorter showers and turning off taps – vital for the city’s future.