Conservationists are concerned about plans to turn an old coal mine into a lake. 

Engie, the French energy company that owns the former Hazelwood coal mine in Victoria's Latrobe Valley, plans to spend $1 billion filling the site with water to create a lake. 

However, a conservation group has raised serious concerns about the proposal. The Hazelwood mine and adjacent power station were shut down in 2017, and Engie is now seeking to rehabilitate the area. 

The proposed lake would hold 725 gigalitres of water, which is more than the volume of Sydney Harbour. 

The project is currently under review by the Victorian and federal governments. The state government has instructed Engie to submit an environmental effects statement (EES). 

Environmental groups are worried that there will not be enough water available in local waterways to fill the mine over the coming decades. 

They also fear that the plan will result in the contamination of local waterways. Of particular concern is the ash landfill, which contains the toxic by-products of coal-fired power generation.

Engie environmental expert David McGavin has stated that the company is working on a plan to prevent ash from the landfill from leaching into the lake. He has assured the public that the company is committed to creating a non-polluting solution. 

If approved, Engie plans to use commercially available water and its existing entitlements from the Latrobe River system to fill the mine. 

Currently, there are 98 gigalitres of water in the mine, which sits above two aquifers that naturally fill it. 

However, Environmental Justice Australia lawyer Chloe Badcock has expressed concerns about the plan, saying that it is a short-term solution with detrimental consequences for the environment. Badcock argues that the proposal will drain water resources and pollute nearby water systems. 

Meteorologists predict extreme heat and dry conditions this year and beyond, as three years of wet weather come to an end. 

Badcock says that her organisation is concerned that the proposed lake will put more stress on nearby water systems at a time when water shortages are projected for the next few years.

According to Badcock, the scoping requirements released by the state government for the environmental effects statement revealed that there are safer and more viable alternatives that Engie needs to consider. 

“All we're asking is for a better rehabilitation option that protects the community and our river systems and safer alternatives to diverting the Morwell River,” she said. 

“[This could include] the use of recycled or desalinated water or considering other rehabilitation options as well.” 

The Victorian planning minister is expected to review the ESS after public hearings next year. 

Engie is awaiting approval to move forward with its plan to fill the mine.