Conservationists are concerned about the latest Environmental Impact Statement (EIS) for the Federal Government's Snowy 2.0 project.

The EIS for the main works is now on public display, but exploratory works for the $5 billion hydro power project are already underway.

It includes a proposal to clear an area in the Kosciuszko National Park.

The EIS outlines a “disturbance footprint” of 1,680 hectares, around 0.25 per cent of Kosciuszko National Park.

National Parks Association executive officer Gary Dunnett described it as “the largest … most destructive development in a national park ever”.

“It's somewhat disingenuous to keep talking about a small percentage of what's one of the very largest national parks in NSW,” he said.

“To put it in context, that's the equivalent of saying that we're going to clear fell all of Sydney Harbour National Park, plus all of Lane Cove National Park, plus all of Kamay-Botany Bay National Park, plus all of Georges River National Park, plus Towra Point Nature Reserve, and a sprinkling of smaller nature reserves.

“What's been revealed last week through the main work's EIS is in fact even worse than our worst imaginings for this project.”

The parent company in charge of the project, Snowy Hydro, says the clearing is only required for the construction phase of the project, and that it will rehabilitate sites once they are no longer needed.

Snowy Hydro manager of water and environment Andrew Nolan said most of the project is underground or using already disturbed sites.

“We firmly believe that given our long track record of existing and operating in the national park now for many decades, and the inherent design of the project, we can balance those short-term construction impacts with the much broader benefits the project brings,” he said.

“We're confident we'll be able to leave it in a better state than how we're finding it today.”

Snowy Valleys Council Mayor James Hayes said “there are a few greater concerns in the national park that need immediate attention”.

“I would say that that would be weeds and feral animals, and I would say unless that's addressed you're clutching at straws with just a few square kilometres of degradation compared to thousands of square kilometres being ravaged by introduced species,” Cr Hayes told reporters.

The new documents cover the main works of the Snowy 2.0 project, but not the transmission lines.

Two more EIS documents are still coming: one for the concrete tunnel linings for the main works and another relating to the proposed underground power station.

Mr Dunnett criticised the approach of developing multiple statements.

“We've had this little drip feed, this death by a thousand EISs approach, where we haven't been given a full picture of the total impacts of this proposal,” he said.