Thirty Years Ago, Perth's Mundaring Weir Overflowed Following Good Winter Rains

Perth looks back to the day when Mundaring Weir last overflowed. Thirty years ago, Perth's Mundaring Weir overflowed following good winter rains. The visitors who flocked to see the spectacle had no idea it would never happen again.

Mundaring Weir overflowed for the last time in 1996. Thirty years ago, Jens Jorgensen, the owner of the Mundaring Weir Hotel, noticed the water levels in the dam were rising every day. Over almost a month, he went down and recorded how far the water was from the top, a record he saved on a board in the bar of the hotel, which he still owns and runs. "I measured it from the top of the wall.

I wasn't supposed to do that, but I dropped a tape down and measured it up, Mr Jorgensen recalled. Jens Jorgensen with the board in his pub showing the countdown to the overflow. ( ABC News: Emma Wynne ) When he first measured, it was 1,800mm from the top, and day by day, amid strong rainfall, the level grew higher.

On Sunday, September 1, 1996, it was just 30mm from spilling over the top, and anticipation was building in Perth that the dam was going to overflow for the first time in years. It took another two days to reach those last 3 centimetres, but when it did, on September 3, the event was a sensation. Mundaring Weir in September 2026. The water level is far from reaching the top.

( ABC News: Emma Wynne ) Thousands of people flocked to the hills to see the spectacle. Visitors flocked to see the weir overflow in 1996, but were not allowed on the walkway." "It was turmoil … people just started to drive up, and I know the police had quite a few issues with parking, Mr Jorgensen said. "It was something completely different, and you know, I found it very exciting.

The water overflowed and spilled down into the Helena riverbed for two weeks before the level fell. Almost 30,000 people came to see it, but what those thousands of people did not realise was that it was the last time the dam would ever overflow. First constructed to dam the Helena River and supply water to be piped to the Goldfields in 1903, the Mundaring Weir regularly overflowed after it was built, so much so that work began to raise the wall in the 1940s, and was completed in 1951. Overflows continued in the 1950s and 1960s, as rain fell steadily each winter.

Rainfall volume began to drop in the mid 1970s. Prior to 1996, the last overflow had been in 1974. Water pouring down the dam wall during an overflow in the 1970s. In 1996, Diana Frylinck had just started working for the Water Corporation on-site, at what was then the CY O'Connor Museum (now named the No 1 Pump Station) and vividly remembers the spectacle of the overflow. The museum, where she still works today as a senior educational officer for the National Trust, is close to the base of the dam wall. "That's thanks to [engineer] CY O'Connor, one of my heroes, because he designed the wall such that it has a curve, and the idea to dissipate the energy in an overflow, so it just came over calmly and gently.

Diana Frylinck works at the Number 1 Pump Station, now a museum that celebrates the weir and the water pipeline. ( ABC News: Emma Wynne ) It was, she recalled, a "terribly exciting time and her role gave her special access. "We had thousands of visitors coming, and we had to open — from memory it was 8 o'clock in the morning till 6 o'clock at night — to accommodate all these people beating down our door, which was fabulous.

"[Sadly] the walkway across the wall had to be closed, because there were all these thousands of people, and we weren't sure if it would actually hold. Only very special people were allowed to go out and have a look. The far side of the wall and the Helena riverbed today.

( ABC News: Emma Wynne ) For two weeks the water continued to flow and people "parked all over the place", Ms Frylink said. "One of my memories is that one of the visitors who came was actually Alan Bond," she said. That week, he was due to go to court and be sentenced and sent to jail, and I thought, isn't that interesting?

The last thing that you would want to do is actually come and see the dam overflowing, so that was quite an exciting visitor to have. Schoolboys watch the weir overflow in 1935. Although she knew it was a rare sight, Ms Frylinck and the other visitors had no idea that it would be the last time it would happen.