SA Water’s recent $8 million upgrade of the intake and scour valves at Warren Reservoir’s dam has revealed a piece of local history – the Second South Para Bridge emerged from the water’s depths for the first time since the reservoir was initially filled more than 100 years ago.
Built in 1890, the 20-metre-long bridge provided a shorter crossing over the South Para River within the original family property of the reservoir’s namesake – John Warren.
As part of the upgrade, Warren Reservoir reached zero per cent of its capacity following a five-week drawdown of the water level, to enable safe access for crews to the base of the dam wall.
SA Water’s Senior Manager of Capital Delivery, Peter Seltsikas, said the generally intact 133-year-old bridge was a rare and unexpected sight arising from the valve upgrade.
“The discovery only came to light when the local Williamstown and Districts Historical Society reached out to inform us that one of their members recalled a bridge that had become slightly visible during the 1960s drought,” Mr Seltsikas said.
“After the tip off, we conducted sonar testing while the reservoir was at 16 per cent capacity and detected a structure at the bottom of the water resembling a bridge.
“We have since learned it was originally built on the family property of John Warren – a former councillor and member of the Legislative Council, who the reservoir is named after – with the entire structure fully resurfacing for the first time since it was flooded by the reservoir’s filling.”
Mr Seltsikas said the deck, pylons and substructure appear to be mainly intact, and it’s likely the white sections of the parapet have washed away over time.
“Despite it no longer carrying a horse and cart over the old river, it’s helped provide habitat and shelter for the reservoir’s fish as we’ve caught a large number in and around the bridge during our relocation activities,” Mr Seltsikas said.
Mr Seltsikas said surprisingly, this isn’t even the first time SA Water has found a bridge at the bottom of a reservoir!
“While delivering a major dam safety upgrade at Kangaroo Creek Reservoir in 2018, the historic Batchelor’s Bridge also emerged from the water as the reservoir was temporarily emptied, with the bridge previously used to convey Gorge Road users across the River Torrens,” Mr Seltsikas said.
As part of the water level’s gradual lowering, around 4.5t of the reservoir’s native fish and turtles have been relocated to the nearby South Para Reservoir, including species like Bony Bream, Murray Cod, Golden Perch and Silver Perch.
Mr Seltsikas said with the reservoir now empty, crews were ramping up to start major construction work as part of replacing the dam’s valves.
“Upgrading the intake and scour valves ensures water can be safely transferred from the reservoir and supplied to our customers into the future,” Mr Seltsikas said.
“With the last of the reservoir’s water released early Mat 2023, crews are set to begin installing a causeway and swing stage scaffolding to safely access the dam wall to decommission the existing valves.
“The valves are connected to a power house near the top of the dam wall and enable water to be transferred from the reservoir to customers for irrigation.
“Two new butterfly valves – which utilise a rotating disc to regulate flow – and a sluice gate scour will be lifted into place with a 220t crane and connected to the existing pipework, and once completed, the valves can be operated automatically from access platforms installed on the dam crest.”
Image caption: Warren Reservoir has now been temporarily emptied to enable SA Water’s upgrade of the dam’s intake and scour valves, revealing the 133-year-old Second South Para Bridge for the first time
