A long-running campaign to drain Lake Pedder and return the natural jewel of Tasmania's south-west to its former glory is ramping up again.

Despite opposition from a small group of environmentalists, the lake's still waters were swallowed up in 1972 by a massive inland sea created to supply the Gordon Power Station.

Harnessing the power of the green movement that emerged from the failed campaign, protesters went on to wage one of the biggest environmental fights in Australia to block the damming of the Franklin River.

Now the Tasmanian Greens have vowed to put the issue back on the political agenda.

Greens MP Nick McKim has called on Hydro Tasmania to conduct a feasibility study.

"What we really need now is a much broader, much more well-informed debate and the government has a real role to play here," he said.

"That's why we need the government to support Hydro Tasmania to step in here and do some work on things like technical feasibility, engineering design and potential costings."

More than 43 years after the lake, with its striking pink sands was flooded, the original campaigners remain determined to restore what was lost to the Hydro scheme expansion.

Adam Beeson, of the Lake Pedder Restoration Committee, said public support for the idea is growing.

Campaigners want to drain and restore Tasmania's Lake Pedder's pristine pink sandy beach.

"There's no shying away from the fact that it is a mega project and would require an enormous amount of planning, risk management, before the plug was pulled," he said.

It is not the first push to restore Lake Pedder.

A 1995 federal inquiry found it was technically feasible, but too expensive.

A predicted glut of electricity has sparked renewed interest in the idea.

"This is the time for this debate to be had," Mr McKim said.

Under the committee's plan, Lake Pedder would be gradually drained back into the surrounding Serpentine and Huon dams, exposing the pink sands of the beach and its valley once again.

"It's really important that the government, Hydro and other important players in this have an open mind and look at this proposal afresh," Mr Beeson said.

The Premier, Will Hodgman, has poured cold water on the idea, but is not ruling out considering other options.

"I can understand people's concerns and I accept the decisions made in the past don't meet with everyone's approval," he said.

Lake Pedder supplies about half the inflows to the Gordon Power Station which accounts for about 5 per cent of Hydro Tasmania's revenue.

"It's important infrastructure for our energy sector, we can't ignore that," Mr Hodgman said.

There was strong opposition to the plan to flood Lake Pedder. ( "Whatever Happened to Brenda Hean" movie )

Conservative estimates put the potential cost at $100 million, but campaigners maintain it would be worth it.

"As an asset it will return better for Tasmania restored, than in its current situation," Mr Beeson said.

Mr McKim agrees the benefits would be wide-ranging.

"It will also necessarily mean that Tasmania will become a centre of excellence for ecological restoration," he said.

"This will be one of the biggest rehabilitation projects ever undertaken."

The latest push comes as the government considers changes to the management of Tasmania's World Heritage Wilderness Area and allowing small scale developments in national parks.

Environmentalists insist the debate about Lake Pedder's future should include discussion about how it would be used and protected long term if it was restored.

The original Lake Pedder left a strong impression on those who spent time there.

Melva Truchanas visited often.

"There's never been anything that's come up to it in its quality, in its serenity. Someone used to say it was like a Wagnarian opera, and I still get upset," she said.

Photographs by her late husband, Olegas Truchanas, helped put the majestic natural feature on the world's map during the battle to save it.

Ms Truchanas is hopeful future generations will be able to enjoy the place once more.

Divers have found the water has preserved, rather than destroyed the natural features, fuelling hopes of revealing them once again.

"Those sand dunes are still intact, it's a sleeping giant, and it will surface some time," said Ms Truchanas.