Experts say it will take as long as 300 years to properly rehabilitate a Victorian wetland that has been devastated by a water authority.

Key points: Barwon Water used the Big Swamp aquifer under the Otways periodically for 40 years as a back-up supply for Geelong

Barwon Water used the Big Swamp aquifer under the Otways periodically for 40 years as a back-up supply for Geelong The pumping drained waterways and led to toxic soils and fish kills

The pumping drained waterways and led to toxic soils and fish kills Local environmental groups propose creating a subterranean national park to protect the wetland, and fear Barwon Water could resume pumping too soon

Barwon Water has been ordered by the state government to remediate the area it damaged in the Otways known as Big Swamp.

The water authority pumped water out of aquifers in the region, on-and-off for about 40 years, as a back-up water supply for Geelong residents.

It led to: drained waterways, toxic soil, fish kills, increased bushfire risk, and a total destruction of habitat for platypuses and other wildlife.

After many years of denying its culpability, Barwon Water eventually admitted fault, and withdrew its application to renew its licence to pump groundwater from the area in March this year.

But two environmental campaigners in the region said Barwon Water had already indicated it hoped to pump more water from the region once its remediation commitments were completed.

The only hope for protection, said one campaigner, was the creation of a "subterranean national park" covering the Otways' groundwater reserves.

Environmentalists fear that areas of the Otways could become "a desert" if aquifers are not allowed to refill. ( ABC South West Vic: Emma Nobel )

Going underground

Malcolm Gardiner is president of the Land and Water Resources Otway Catchment (LAWROC), a Landcare group which waged a war against Barwon Water for more than a decade after noticing increased acid levels and depleted flows in rivers and creeks in part of the Otways, south of Colac.

He said he has proposed the creation of a new classification — a subterranean national park — as the only away to protect the impacted groundwater areas for the future.

"The Otways will turn into a desert if they continue pumping," Mr Gardiner said.

"The Gellibrand [river] will turn into an acid bath: vegetation will die out, water supply will disappear for the western district. It [will be] the biggest time bomb for fire in the Western District."

He said this protection would allow the wetlands, springs and waterways to replenish, providing for farmers who use the surface water, as well as the environment.

Mr Gardiner said the state Environment Department's own information to the Water Minister showed it would take at least 309 years for the aquifers to return to their pre-extraction levels.

The Landcare group for the Otway Catchment says this is what Big Swamp used to look like before groundwater pumping. ( Matt Neal )

He was concerned by comments from a Barwon Water representative that suggests the water authority plans to apply to pump water from the bore field within five or 10 years of completing remediation in the Big Swamp area.

Geelong Environment Council secretary Joan Lindross backed Mr Gardiner's fears.

"At a Barwon Water talk just recently, about their water futures, a Barwon Water representative said 'we've got to fix it up before we use it again'," Ms Lindross said.

"I thought that really indicated that they haven't got the message that you can't use these aquifers without having a bad effect."

Barwon Water refused to completely rule out future pumping from the bore field it had damaged.

"We are not currently contemplating applying for a licence," Barwon Water general manager of strategy, systems and environment Seamus Butcher said.

"Our focus is on remediation and we have committed to completing remediation before we even consider whether or not to apply for another licence."

A long recovery process

Malcolm Gardiner's idea of a subterranean national park had its supporters and detractors.

Geoff Bilby, a former state Environment Department employee who helped manage the Otways, said there are existing land classifications that could be used to protect the bore fields in the region, rather than creating a new one.

"The area could be protected [as] a 'special purposes reserve'," Mr Bilby said.

"[These reserves] have to be managed in perpetuity as a natural site, so nothing can be done which would impact on their value. They're to be used as a measure, to measure against changes to the environment in other areas.

"Malcolm's on the track to try and protect that, and in protecting the water he's protecting the flora and fauna and allowing it to recover.

"It's going to be a long recovery process. That area that's been damaged is going to take hundreds of years to recover from what's been done with it."

The Otways is at the centre of a proposal to introduce "subterranean national parks" to protect underground aquifers. ( Supplied: Luke Edwards )

Ms Lindross said the Geelong Environment Council would support a proposal for a subterranean national park "very strongly".

"I think it's fantastic," she said.

"[Malcolm Gardiner] has fought for years to get Barwon Water to even recognise it was their extraction of water that caused the problems.

"It's affected the vegetation, it's affected the springs where people get water for stock, it's affected the Barwon River. It's a really major concern."

A global issue

Professor Richard Bush from Monash University's Sustainable Development Institute said the idea of a subterranean national park was an interesting concept that has national and even international ramifications.

"I haven't seen anything quite like [what happened at Big Swamp], but the issue of over-extraction of groundwater is widespread across Australia and it's a problem that needs to be managed at an international level," Professor Bush said.

"The growing problem is that water is becoming more scarce at a national level and also a global level and our groundwater resources are finite.

"If you're extracting groundwater you can have an impact on the environment. This is a significant problem and something people need to prepare for.

"Groundwater is one of those difficult things to manage because it is out of sight: it's difficult to measure, it's complex to monitor and evaluate and I do think we need to get smarter in the way we assess these types of resources and/or conserve the groundwater for the environment.

"I like the idea of a subterranean national park.

"In the Otways, it's an amazing environment, with wonderful stands of vegetation, there's a lot of biodiversity in the region, there's a lot of tremendous environmental and social values to preserve in that region.

"Therefore this idea might just legs because you're more or less saying that 'this system and landscape, [which] the community relies on, is highly dependent on a healthy groundwater system."