The flooding of Lake Pedder half a century ago was an emblematic moment in the history of Australian environmentalism.
A glacial outwash lake deep in Tasmania’s south-west that was celebrated for its pink quartzite beach, Pedder and 230 sq km of forest and wildlife were drowned in 1972 after the construction of dams for the Gordon hydroelectric power scheme. A campaign to save the lake failed, but it is now regarded as a galvanising moment that led to the creation of the world’s first green political party and the successful drive to stop the damming of the Franklin River a decade later.
For decades, there has been a movement to restore the lake to its pre-impoundment health. The Lake Pedder Restoration committee, led by former Australian Greens leader Christine Milne, argues that the electricity created is not essential for energy security (because windfarms added in recent years offer more generation) and does not justify the loss of a central attraction in what became a world heritage wilderness area.
The Tasmanian Liberal government disagrees. It argues Lake Pedder is an important storage site for the Gordon scheme, and helps the state run almost entirely on renewable hydro power. Hydro Tasmania, the state’s publicly owned electricity generation business, says that together the neighbouring Pedder and Gordon lakes offer Australia’s largest water storage capacity. The state energy minister, Guy Barnett, leans hard on the need to expand renewable electricity.
But campaigners see an opportunity. Two of the dams that led to Pedder’s flooding are ageing and next to a fault line – a crack in the Earth’s crust – formed about 540m years ago. The fault was considered inactive when the dams were built but recent analysis says otherwise. A 2017 report by the state’s auditor general found that both dams should be considered “high risk”.
Though the likelihood of an earthquake is low – there are believed to have been only three of a magnitude greater than six in at least the past 48,000 years – any rupture could lead to the flooding of areas south of Hobart, particularly the town of Huonville, which has a population of about 3,000.
The auditor general suggested that Edgar Dam, which is closest to the fault, may be “susceptible to liquefaction” (collapse) while the second, Scott’s Peak Dam, was deemed “vulnerable to geological faults”.
Hydro Tasmania has plans to strengthen both dams, starting with a $21m investment in Edgar Dam next year to remove the concrete face of the dam wall and put in gravel filters and supporting rock. A wave barrier will be added to the top of the dam wall. A government estimate in 2019 suggested similar work at Scott’s Peak Dam could cost $50m.
Hydro Tasmania needs to ‘come clean’ on risks, says Milne
The Lake Pedder Restoration committee sees this moment as a fork in the road. Head down one path and the state could spend tens of millions of dollars – Milne estimates more than $100m – to shore up the dams for the indefinite future.
Choose the other and it could set an international example of ecosystem restoration on a large scale, meeting a UN call for national governments to commit to ambitious projects in this decade. It would involve gradually releasing 15m depth of water down surrounding rivers, dismantling the dams and investing in re-establishing what was lost in 1972.
Crucially, the committee says, there is video evidence, shot two years ago, that the near 1km-wide quartzite beach remains intact under the water.
Milne says it was “a beautiful place, and an icon in Australian conservation history” that could be recovered.
“The loss of Lake Pedder is globally recognised as one the great mistakes of the 20th century in an ecological sense,” she says. “Its restoration would catapult Tasmania back into global headlights to say: this is a place of outstanding natural beauty which is now leading the world in ecosystem restoration.”
Milne says the state government and Hydro Tasmania should “come clean” with the public and release their assessments of what could happen in the event of the dams’ failure. She says a benefit analysis is needed to compare decommissioning the dams with ameliorating the risk of an earthquake. Repairing them would provide what she estimates is 57 megawatts of power-generation capacity, equivalent to a small windfarm. The answer, she says, would be “a no brainer”.
Neither the government nor Hydro Tasmania responded directly when asked if such analysis had been carried out. Hydro says it has an emergency plan for each of its dams and that the state emergency service, fire service and police brigade are fully briefed.
“We regularly undertake joint emergency preparedness sessions with these organisations,” the organisation’s spokesperson says.
The director of the Victorian University Energy Policy Centre, Bruce Mountain, believes Lake Pedder’s storage has value in the national electricity grid, but says its removal would not be an energy-security issue. He agrees with Milne that the energy it generates could be easily replaced.
He says Tasmania has done next to nothing to promote rooftop solar uptake, despite its decent electricity potential, particularly in the north of the state. Mountain says a scheme that encouraged households and businesses to put up panels could fill the gap and provide cheaper power.
Pedder ‘vital part’ of energy package, insists Barnett
Hydro Tasmania says any decision about the future of Lake Pedder rests with the government, but argues Edgar Dam plays an essential role in ensuring adequate energy storage. A Hydro spokesperson says the lake supplies 42% of inflows to the 450MW Gordon power scheme, which is “one of the largest and most important generation assets” the utility has. The scheme is one of only two sites in the state with multi-year water-storage capacity.
“As Australia transitions to renewable energy, long-duration energy storage, like that provided by Lake Pedder, is essential to fill the gaps when wind and solar power aren’t available,” a spokesperson says.
Hydro also implicitly dismisses the suggestion that this moment is as decisive as the restoration committee claims. It says the Edgar Dam redevelopment will go ahead and is expected to cost the full $21m, but that after an “expert reassessment”, work on Scott’s Peak Dam is not an immediate priority. Its spokesperson says: “It is no longer appropriate to consider both projects in combination.”
The Tasmanian government declined to answer questions about the potential benefits of the lake’s restoration or the earthquake risk. Barnett instead focuses on the state’s commitment to get more than 100% of its electricity from renewable energy, including meeting a legislated target of 200% – doubling current generation – by 2040.
The government is committed to the Battery of the Nation and Marinus Link projects, under which the state would help replace the mainland’s coal-fired power plants by building pumped hydro storage and wind energy capacity that would send electricity across Bass Strait via a new undersea transmission cable. Both projects are yet to be funded.
Should Tasmania focus on generating power for local use, developing green industries on a scale suitable for the country’s smallest state and protecting sites such as Lake Pedder? Or should it build new renewable energy infrastructure, including in some undeveloped and environmentally sensitive areas, to help the country run on clean electricity?
While the Greens are focused on the urgency of the national transition to renewable energy, Milne is firmly in the former camp – as is much of the Tasmanian environmental movement. The Liberal government, despite its federal counterparts’ reluctance to embrace renewables, is in the latter.
In Barnett’s words: “Tasmania is poised to be the renewable powerhouse of the country” and Lake Pedder is “a vital part of that overall package”.
“In Tasmania, we want to move forward and grow our renewable energy credentials, not go backwards,” he says.
Milne says there is another path, one that balances renewable energy with protection, and wants the federal government to step in. “It would be a brilliant decision for the nation’s global standing in demonstrating our stewardship of the world heritage area,” she says. “And it would guarantee community safety by removing any risk of the dams failing. It’s a win-win scenario.”
